Nine mixed ligand complexes of dioxomolybdenum(VI) with 5-bromo and 3,5- dibromo salicylaldehyde 4-(H/C6H5)-S-propylthiosemicarbazones (H2L) were prepared with the formula [MoO2(L)D] (D = pyridine, methanol, n-propanol or 2-propen-1-ol). Characterization of the compounds was accomplished by means of elemental analysis, IR and H-1 NMR spectroscopy, and in one example, a single crystal X-ray structure determination. The dibasic thiosemicarbazone ligands are coordinated to dioxomolybdenum(VI) cation through ONN set, while the sixth coordinated site of the molybdenum is occupied by the second ligand (D). The MoO2 core of the complex is in cis-dioxomolybdenum structure with angles 105.8 angstrom, the crystal analysis of complex 1a indicated a dimer structure consisted of two 1a molecules by hydrogen bond with 2.054 a. The decisive roles of S-alkyl groups on the bond lengths of Mo-N-py coordination the intermolecular hydrogen bonds were evaluated.