Rice grain yield and quality are affected by the high temperature stress to a large extent. Four promising backcross introgression lines (BC2 F8 ) of KMR-3R/N22 carrying qHTSF1.1, qHTSF4.1 and HT Score QTLs were evaluated for high-temperature induced rice grain and cooking quality during Rabi 2021. Late-sown staggered planting was adopted to ensure uniform high-temperature stress on the improved restorers along with the parents used, which resulted in significant yield loss and grain quality degradation due to hightemperature stress. For cooking quality metrics, ANOVA showed significant variation among genotypes (G), treatments (T), and G×T. Among the backcross introgression lines (BILs), RP6338-9 possesses qHTSF4.1 noted to be promising for grain quality traits under high temperature stress.