The perovskite solid solution composition Sr(Ti0.5Zr0.5)O-3 (STZ (ss)) has been synthesized from the mixture of SrCO3. TiO2 and ZrO2 powders through solid-state reaction. The phase formation mechanism and kinetics were investigated using TG/DSC, XRD. SrCo3 in the precursor decomposes at relatively lower temperature than pure powder decomposition, due to the presence of acidic TiO2. Upon calcinations of the precursor SrTiO3 (ST) and SrZrO3 (SZ) were formed separately in the system. Then ST defuses in to SZ to form STZ (ss). ST formation started at lower temperature (800 degrees C with lower activation energy (47.274 kcal/mol) than SZ. SZ formation started at 1000 degrees C with high activation energy (65.78 kcal/mol). STZ (ss) formation started from 1500 degrees C with very high activation energy (297.52 kcal/mol). It is concluded that solid solution formed coherently with SZ lattice by the diffusion of Ti in to the SZ. (c) 2005 Published by Elsevier Ltd.