An investigation was carried out utilizing 148 recombinant inbred lines of rice derived from cross between IR 64 and high temperature stress / heat tolerant donor N 22 at Agricultural College and Research Institute, Madurai, Tamil Nadu. The aim of the study was to assess the extent of variability in order to identify high temperature tolerant lines that could be utilized either directly or in hybridization programme to keep pace with the global climate changes. The variability studies indicated that single plant yield, number of ill-filled grains panicle-1, number of productive tillers plant-1, number of filled grains panicle-1, 1000 grain weight, flag leaf length and flag leaf width had relatively high PCV and GCV estimates. High genetic advance along with high heritability were found for all the characters except days to 50 per cent flowering and number of ill-filled grains indicating the presence of additive gene action for controlling these traits. High positive direct effect with single plant yield was exerted by the traits viz., number of productive tillers plant-1, number of filled grains panicle-1 and spikelet fertility.