A series of methylbismuth(III)O,O-alkylenedithiophosphates of the type [MeBi{S2P(O-G-O)}2][where G = CH 2 CH(CH 3 ) (1), (CH 2 ) 4 (2), CH 2 CH 2 CH(CH 3 ) (3), CH(CH 3 )CH(CH 3 ) (4), CH 2 CHCH 2 CH 3 (5), CH(CH 3 )CH 2 C(CH 3 ) 2 (6) and C(CH 3 ) 2 C(CH 3 ) 2 (7)] have been isolated by the reaction of methylbismuth(III) dichloride with potassium salt of O,O-alkylenedithiophosphoric acids in 1 : 2 molar ratio in anhydrous benzene. These newly synthesized derivatives were characterized by elemental analyses, FT IR and multinuclear NMR ( 1 H, 13 C and 31 P) spectral studies. Thermogravimetric analysis of 6 has shown a single-step decomposition of complex to Bi 2 S 3 at 154.3 • C. Transformation of 2 and 6 to pure Bi 2 S 3 was carried out successfully at refluxing xylene temperature (142 • C) as revealed by XRD and SEM analyses.