Interaction of Te(IV) with excess thioglycolic acid (TGA) in strongly acid media leads to formation of yellow diamagnetic soluble S-ligated thioglycollato-tellurium(II) neutral and anionic complexes. The neutral bis-complex is highly unstable with respect to autodecomposition to Te(O) and dithiodiglycolic acid but the anionic higher complexes are stable in absence of competing ligands. The solid H2[TeII(TGA-H)4] was isolated and characterised. Unlike with Te(II)-thiourea complexes, presence of halides did not stabilise but actually destabilised the Te(II)-TGA system, the effect being I ≫ Br ≫ Cl. Addition of thiourea also caused decomposition of the Te(II)-TGA system. The results have been rationalised on the basis of the instability of the Te(II)-(TGA-H)2 species with respect to an internal redox reaction. Addition of Hg(II) to Te(II)-TGA systems caused oxidation of Te(II) to Te(IV) in absence of halide ions and interestingly to the formation of the Hg(II) chalcohalides of composition, Hg3Te2X2 (X = Cl,Br,I) in presence of halides. © 1973.