The crystal structures of the [TlMe₂L] and [SnMe₂L₂](L = pyridine-2-thiolate) have been determined. Dimethyl(pyridine-2-thiolato)thallium(III) crystallizes in the monoclinic space group P2₁/n(no 14) with a= 8.169(1), b= 13.214(1), c= 8.876(2)Å, β= 104.61 (1)°, and Z= 4. Refinement converged to R= 0.047 for 1 531 independent observed reflections. The thallium atom co-ordinates to the two methyl carbons [Tl–C 2.159(8) and 2.199(8)Å], to the pyridine nitrogen [Tl–N 2.494(7)Å], and to two sulphur atoms [Tl–S 3.160(3) and 2.870(2)Å]. Dimethylbis(pyridine-2-thiolato)tin(IV) crystallizes in the monoclinic space group P2₁/m(no 11) with a= 6.664(5), b= 17.342(5), c= 6.943(3)Å, β= 112.53(5)°, and Z= 2. Refinement converged to R= 0.038 for 1 105 independent observed reflections. The tin atom co-ordinates to the two methyl carbons [Sn–C 2.133(9)Å], the two pyridine nitrogens [Sn–N 2.702(5)Å], and the two sulphur atoms [Sn–S 2.487(2)Å]. The structural characteristics of the free ligand are compared with those of the co-ordination compounds, and the mass and ¹³C n.m.r. spectra of the two complexes are compared.