Some thermal (TGA and DSC) studies of polysilanes viz., polydimethylsilane (PDMS), copolymer of polydimethyl-methylphenylsilane (PDMMPS), polydimethyl-methylsilane (PDMMS), polydimethyl-methylvinylsilane (PDMMVS) and polycarbosilanes (PCS) synthesized using PDMS have been carried out. PDMS and PDMMPS found more suitable for synthesizing meltable and soluble polycarbosilanes and gave better char yield compared to PDMMVS and PDMMS. The polydimethyl-methylvinylsilane (PDMMVS) did not show any melting behavior and cured at similar to166 degreesC as an endotherm was noticed in DSC. The PCS-N (mp similar to124 degreesC) on heating up to 450 degreesC become non-meltable but remain soluble in common organic solvents, which on further heating up to similar to650 degreesC become non-meltable and non-soluble. The thermal recycling of the PCS-N at similar to350 degreesC minimized the exotherms as observed in the DSC. The XRD studies revealed that the alpha-SiC and beta-SiC formation took place at similar to930 and 1250 degreesC, respectively as reported earlier too. (C) 2004 Elsevier B.V. All rights reserved.