diff --git a/src/main/java/de/ids_mannheim/korap/query/serialize/CQLTree.java b/src/main/java/de/ids_mannheim/korap/query/serialize/CQLTree.java
new file mode 100644
index 0000000..97537a4
--- /dev/null
+++ b/src/main/java/de/ids_mannheim/korap/query/serialize/CQLTree.java
@@ -0,0 +1,200 @@
+package de.ids_mannheim.korap.query.serialize;
+
+import java.io.IOException;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.z3950.zing.cql.CQLAndNode;
+import org.z3950.zing.cql.CQLBooleanNode;
+import org.z3950.zing.cql.CQLNode;
+import org.z3950.zing.cql.CQLOrNode;
+import org.z3950.zing.cql.CQLParseException;
+import org.z3950.zing.cql.CQLParser;
+import org.z3950.zing.cql.CQLRelation;
+import org.z3950.zing.cql.CQLTermNode;
+import org.z3950.zing.cql.Modifier;
+
+import de.ids_mannheim.korap.util.QueryException;
+
+public class CQLTree extends AbstractSyntaxTree {
+	
+	private static final String VERSION_1_1 = "1.1";
+    private static final String VERSION_1_2 = "1.2";
+    private static final String INDEX_CQL_SERVERCHOICE = "cql.serverChoice";
+	private static final String INDEX_WORDS = "words";
+	private static final String TERM_RELATION_CQL_1_1 = "scr";
+    private static final String TERM_RELATION_CQL_1_2 = "=";
+    private static final String SUPPORTED_RELATION_EXACT = "exact"; // not in the doc    
+    private static final String OPERATION_OR = "operation:or";
+    private static final String OPERATION_SEQUENCE = "operation:sequence";
+    private static final String KORAP_CONTEXT = "http://ids-mannheim.de/ns/KorAP/json-ld/v0.1/context.jsonld";
+    
+	private LinkedHashMap<String,Object> requestMap;
+	private String version;
+	private boolean isCaseSensitive;
+	private StringBuilder sb;
+	
+	public CQLTree(String query) throws QueryException {
+		this(query, VERSION_1_2, true);
+	}
+	
+	public CQLTree(String query, String version, boolean isCaseSensitive) throws QueryException {
+		this.sb = new StringBuilder();
+		this.version = version;
+		this.isCaseSensitive = isCaseSensitive;
+		this.requestMap = new LinkedHashMap<String,Object>();		
+		requestMap.put("@context", KORAP_CONTEXT);
+		process(query);
+	}
+	
+	
+	@Override
+	public Map<String, Object> getRequestMap() {		
+		return this.requestMap;		
+	}
+
+	@Override
+	public void process(String query) throws QueryException {
+		CQLNode cqlNode = parseQuerytoCQLNode(query);
+		parseCQLNode(cqlNode);
+		String serializedQuery = sb.toString();	
+		requestMap.put("query", serializedQuery);		
+	}
+	
+	private CQLNode parseQuerytoCQLNode(String query) throws QueryException{		
+		try {
+			int compat = -1;
+			switch (version) {
+	            case VERSION_1_1:
+	                compat = CQLParser.V1POINT1;
+	                break;
+	            case VERSION_1_2:
+	                compat = CQLParser.V1POINT2;
+            }			
+			return new CQLParser(compat).parse(query);			
+			
+		} catch (CQLParseException | IOException e) {
+			throw new QueryException("Error parsing CQL");			
+		}
+	}
+	
+	private void parseCQLNode(CQLNode node) throws QueryException {		
+		if (node instanceof CQLTermNode){			
+			parseTermNode((CQLTermNode) node);
+		}
+		else if (node instanceof CQLAndNode ){			
+			parseAndNode((CQLAndNode) node);
+		}
+		else if (node instanceof CQLOrNode){
+			parseOrNode((CQLOrNode) node);
+		}
+		else {
+			throw new QueryException(48, "Only basic search including term-only " +
+				"and boolean operator queries (AND and OR) are currently supported.");
+		}
+	}
+	
+	private void parseTermNode(CQLTermNode node) throws QueryException {		
+		checkTermNode(node);        
+        final String term = node.getTerm();
+        if ((term == null) || term.isEmpty()) {
+            throw new QueryException(27, "An empty term is unsupported.");
+        }
+        else if (term.contains(" ")){	           
+        	writeSequence(term);
+        }
+        else {
+        	writeTerm(term);
+        }
+	}
+	
+	private void parseAndNode(CQLAndNode node) throws QueryException {
+		checkBooleanModifier(node);
+		sb.append("{@type=korap:group, operation=");
+		sb.append(OPERATION_SEQUENCE);
+		sb.append(", distances=[{@type=korap:distance, key=t, min=0, max=0}]");
+		sb.append(", operands=[");
+		parseCQLNode(node.getLeftOperand());
+		sb.append(", ");
+        parseCQLNode(node.getRightOperand());
+        sb.append("]}");
+	}
+
+	private void parseOrNode(CQLOrNode node) throws QueryException {
+		checkBooleanModifier(node);
+        sb.append("{@type=korap:group, operation=");
+		sb.append(OPERATION_OR);
+		sb.append(", operands=[");
+		parseCQLNode(node.getLeftOperand());
+		sb.append(", ");
+        parseCQLNode(node.getRightOperand());
+        sb.append("]}");      		
+	}
+	
+	private void writeSequence(String str){
+		String[] terms = str.split(" ");
+		sb.append("{@type=korap:group, operation=");
+		sb.append(OPERATION_SEQUENCE);
+		sb.append(", operands=[");
+		
+		int size = terms.length;
+	    for (int i = 0; i < size; i++) {
+	    	writeTerm(terms[i]);
+	    	if (i < size-1)
+	    		sb.append(", ");
+        }
+	    
+	    sb.append("]}");
+	}
+	
+	private void writeTerm(String term) {		
+		sb.append("{@type=korap:token, wrap={@type=korap:term");
+		if (!isCaseSensitive){
+			sb.append(", caseInsensitive=true");			
+		}		
+		sb.append(", key=");
+		sb.append(term);		
+		sb.append(", layer=orth, match=match:eq}}");		
+	}
+
+	private void checkBooleanModifier(CQLBooleanNode node) throws QueryException {		
+		List<Modifier> modifiers = node.getModifiers();
+        if ((modifiers != null) && !modifiers.isEmpty()) {
+            Modifier modifier = modifiers.get(0);            
+            throw new QueryException(20, "Relation modifier \"" +
+            		modifier.toCQL() + "\" is not supported.");
+        }
+	}
+	
+	private void checkTermNode(CQLTermNode node) throws QueryException {
+		// only allow "cql.serverChoice" and "words" index
+        if (!(INDEX_CQL_SERVERCHOICE.equals(node.getIndex()) ||
+                INDEX_WORDS.equals(node.getIndex()))) {
+            throw new QueryException(16, "Index \""+node.getIndex()+"\" is not supported.");
+        }
+        // only allow "=" relation without any modifiers
+        CQLRelation relation = node.getRelation();
+        String baseRel = relation.getBase();
+        if (!(TERM_RELATION_CQL_1_1.equals(baseRel) ||
+                TERM_RELATION_CQL_1_2.equals(baseRel) ||
+                SUPPORTED_RELATION_EXACT.equals(baseRel))) {
+            throw new QueryException(19, "Relation \"" +
+                        relation.getBase() + "\" is not supported.");
+        }
+        List<Modifier> modifiers = relation.getModifiers();
+        if ((modifiers != null) && !modifiers.isEmpty()) {
+            Modifier modifier = modifiers.get(0);
+            throw new QueryException(20, "Relation modifier \"" +
+                            modifier.getValue() + "\" is not supported.");
+        }
+	}
+	
+	public String getVersion() {
+		return version;
+	}
+
+	public void setVersion(String version) {
+		this.version = version;
+	}
+}
diff --git a/src/test/java/CQLTest.java b/src/test/java/CQLTest.java
new file mode 100644
index 0000000..ef778b3
--- /dev/null
+++ b/src/test/java/CQLTest.java
@@ -0,0 +1,130 @@
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+
+import org.junit.Test;
+import org.z3950.zing.cql.CQLParseException;
+
+import de.ids_mannheim.korap.query.serialize.CQLTree;
+import de.ids_mannheim.korap.util.QueryException;
+
+
+public class CQLTest {
+	
+	String query;
+	
+	@Test
+	public void testBooleanQuery() throws CQLParseException, IOException, QueryException{		
+		query="((Sonne) or (Mond)) and (scheint)";		
+		String jsonLd = 
+			"{@type=korap:group, operation=operation:sequence, distances=[" +
+				"{@type=korap:distance, key=t, min=0, max=0}" +
+				"], operands=[" +
+					"{@type=korap:group, operation=operation:or, operands=[" +
+						"{@type=korap:token, wrap={@type=korap:term, key=Sonne, layer=orth, match=match:eq}}," +
+						"{@type=korap:token, wrap={@type=korap:term, key=Mond, layer=orth, match=match:eq}}" +
+					"]}," +
+					"{@type=korap:token, wrap={@type=korap:term, key=scheint, layer=orth, match=match:eq}}" +
+			"]}";
+		CQLTree cqlTree = new CQLTree(query);		
+		String serializedQuery = cqlTree.getRequestMap().get("query").toString();
+		assertEquals(jsonLd.replace(" ", ""), serializedQuery.replace(" ", ""));
+		
+		
+		query="(scheint) and ((Sonne) or (Mond))";
+		jsonLd = 
+				"{@type=korap:group, operation=operation:sequence, distances=[" +
+						"{@type=korap:distance, key=t, min=0, max=0}" +
+					"], operands=[" +
+						"{@type=korap:token, wrap={@type=korap:term, key=scheint, layer=orth, match=match:eq}}," +
+						"{@type=korap:group, operation=operation:or, operands=[" +
+							"{@type=korap:token, wrap={@type=korap:term, key=Sonne, layer=orth, match=match:eq}}," +
+							"{@type=korap:token, wrap={@type=korap:term, key=Mond, layer=orth, match=match:eq}}" +
+					"]}" +
+				"]}";
+		cqlTree = new CQLTree(query);		
+		serializedQuery = cqlTree.getRequestMap().get("query").toString();
+		assertEquals(jsonLd.replace(" ", ""), serializedQuery.replace(" ", ""));
+		
+	}
+	
+	@Test
+	public void testOrQuery() throws CQLParseException, IOException, QueryException{
+		query = "(Sonne) or (Mond)";		
+		String jsonLd = 
+			"{@type=korap:group, operation=operation:or, operands=[" +
+				"{@type=korap:token, wrap={@type=korap:term, key=Sonne, layer=orth, match=match:eq}}," +
+				"{@type=korap:token, wrap={@type=korap:term, key=Mond, layer=orth, match=match:eq}}" +
+			"]}";		
+		
+		CQLTree cqlTree = new CQLTree(query);		
+		String serializedQuery = cqlTree.getRequestMap().get("query").toString();
+		assertEquals(jsonLd.replace(" ", ""), serializedQuery.replace(" ", ""));
+		
+		query="(\"Sonne scheint\") or (Mond)";		
+		jsonLd = 
+			"{@type=korap:group, operation=operation:or, operands=[" +
+				"{@type=korap:group, operation=operation:sequence, operands=[" +
+					"{@type=korap:token, wrap={@type=korap:term, key=Sonne, layer=orth, match=match:eq}}," +
+					"{@type=korap:token, wrap={@type=korap:term, key=scheint, layer=orth, match=match:eq}}" +
+				"]}," +
+				"{@type=korap:token, wrap={@type=korap:term, key=Mond, layer=orth, match=match:eq}}" +
+			"]}";
+		
+		cqlTree = new CQLTree(query);		
+		serializedQuery = cqlTree.getRequestMap().get("query").toString();
+		assertEquals(jsonLd.replace(" ", ""), serializedQuery.replace(" ", ""));
+				
+		query="(\"Sonne scheint\") or (\"Mond scheint\")";		
+		jsonLd = 
+			"{@type=korap:group, operation=operation:or, operands=[" +
+					"{@type=korap:group, operation=operation:sequence, operands=[" +
+						"{@type=korap:token, wrap={@type=korap:term, key=Sonne, layer=orth, match=match:eq}}," +
+						"{@type=korap:token, wrap={@type=korap:term, key=scheint, layer=orth, match=match:eq}}" +
+					"]}," +
+					"{@type=korap:group, operation=operation:sequence, operands=[" +
+						"{@type=korap:token, wrap={@type=korap:term, key=Mond, layer=orth, match=match:eq}}," +
+						"{@type=korap:token, wrap={@type=korap:term, key=scheint, layer=orth, match=match:eq}}" +
+					"]}" +
+				"]}";
+		cqlTree = new CQLTree(query);		
+		serializedQuery = cqlTree.getRequestMap().get("query").toString();
+		assertEquals(jsonLd.replace(" ", ""), serializedQuery.replace(" ", ""));
+	}
+	
+	@Test
+	public void testTermQuery() throws CQLParseException, IOException, QueryException{
+		query = "Sonne";		
+		String jsonLd = "{@type=korap:token, wrap={@type=korap:term, key=Sonne, layer=orth, match=match:eq}}";		
+		CQLTree cqlTree = new CQLTree(query);		
+		String serializedQuery = cqlTree.getRequestMap().get("query").toString();		
+		assertEquals(jsonLd.replace(" ", ""), serializedQuery.replace(" ", ""));
+	}
+	
+	@Test
+	public void testPhraseQuery() throws CQLParseException, IOException, QueryException{
+		query="\"der Mann\"";				
+		String jsonLd = 
+				"{@type=korap:group, operation=operation:sequence, operands=[" +
+					"{@type=korap:token, wrap={@type=korap:term, key=der, layer=orth, match=match:eq}}," +
+					"{@type=korap:token, wrap={@type=korap:term, key=Mann, layer=orth, match=match:eq}}" +
+				"]}";
+		
+		CQLTree cqlTree = new CQLTree(query);		
+		String serializedQuery = cqlTree.getRequestMap().get("query").toString();
+		assertEquals(jsonLd.replace(" ", ""), serializedQuery.replace(" ", ""));
+		
+		
+		query="der Mann schläft";
+		jsonLd = 
+				"{@type=korap:group, operation=operation:sequence, operands=[" +
+					"{@type=korap:token, wrap={@type=korap:term, key=der, layer=orth, match=match:eq}}," +
+					"{@type=korap:token, wrap={@type=korap:term, key=Mann, layer=orth, match=match:eq}}," +
+					"{@type=korap:token, wrap={@type=korap:term, key=schläft, layer=orth, match=match:eq}}" +
+				"]}";
+		
+		cqlTree = new CQLTree(query);		
+		serializedQuery = cqlTree.getRequestMap().get("query").toString();
+		assertEquals(jsonLd.replace(" ", ""), serializedQuery.replace(" ", ""));
+	}	
+}