The effect of initial grain temperature on the combustion response of composite solid propellants (AP/HTPB/RDX/Al) is experimentally investigated using a T-burner. Tests were conducted at different frequencies ranging from 200–400 Hz and at different pressures of 1–8 MPa at different initial propellant temperatures using a novel method (303 K, 243 K and 343 K) for two industrial-grade propellants, propellant-A and propellant-B. The test results revealed that the hot and cold temperatures increase the response. The combustion responses of the propellant-B are lower than propellant-A. Pulsed tests are conducted when the propellant showed low or negative response. This work highlights that the initial grain temperature is a crucial factor in determining the stability of solid rocket motors. The negative response compels us to further investigate toward a better understanding about the unsteady combustion behavior since there is no model available which could predict negative responses as of today. © 2022 Defence Research and Development Organisation.