The invention relates to a method for preparation of ruthenium-based carbene catalysts with a chelating alkylidene ligand (“Hoveyda-type catalysts”) by reacting a penta coordinated ruthenium (II)-alkylidene complex of the type (L) (Py)X1X2Ru(alkylidene) with a suitable olefin derivative in a cross metathesis reaction. The method delivers high yields and is conducted preferably in aromatic hydrocarbon solvents. The use of phosphine-containing Ru carbene complexes as starting materials can be avoided. Catalyst products with high purity, particularly with low Cu content, can be obtained.