[en] Compounds with the MoO₂(L-H)₂ composition, where L is ligand, were separated by the interaction of molybdenum trioxide with isonicotinic acid hydrazide and its derivatives: phthivazide, saluzide larusan. The infrared spectra are taken. On the base of the infrared spectra of the separated complexes a conclusion is made on the method of coordination of ligands to metal. The substances obtained are studied by the X-raying method and their molar electric conductivity is determined. The complex thermolysis products are characterized qualitatively