Pyrolysis experiments were carried out with Sn4R4O6 {R = methyl (1), butyl (2) and phenyl (3)}. The thermal behaviour of the organotin oxides was studied by Thermogravimetric Analysis (TG) with simultaneous Differential Thermal Analysis (DTA) and the residues obtained after decomposition were characterised by X-ray electron probe microanalysis (EPMA), Scanning Electron Microscopy (SEM), X-ray diffraction and Sn-119 Mossbauer spectroscopy. The results have shown that the methyl derivative is the best precursor, producing nanoparticles of pure phase rutile-type tetragonal SnO2 in O-2 with a yield up to 90%. (C) 2003 Elsevier Ltd. All rights reserved.