In the present work, the dynamic characterization of carbon nano tubes (CNT)-reinforced GFRP composite beam under elevated temperature has been investigated experimentally. GFRP composite beams without and with CNT reinforcement have been fabricated using vacuum-assisted hand lay-up technique. Natural frequencies and damping ratio of the composite beams for the first three modes are being measured under clamped-free and clamped–clamped end conditions using experimental modal analysis. Further, the effect of variation of temperature of the GFRP composite beams without and with CNT reinforcement on natural frequencies and damping ratio have been studied. It was observed that the fundamental natural frequency of the CNT-GFRP hybrid composite beam is approximately 17.43% and 18.46% higher than that of GFRP composite beams without CNT reinforcement under CF and CC boundary conditions, respectively. The fundamental natural frequency of CNT-GFRP composite beam decreases by 3.47% and 11.19%, whereas the damping ratio at first mode increases by 22.64% and 35.41% under clamped-free (CF) and CC boundary conditions, respectively when the temperature increased from 30°C to 60°C. POLYM. COMPOS., 40:464–470, 2019. © 2017 Society of Plastics Engineers. © 2017 Society of Plastics Engineers