[en] Experimental measurements of the time variation of gas temperature in a non-equilibrium hydrogen-methane microwave plasma operating at medium pressure and under pulsed mode are presented. The hydrogen plasma is created using a 915 MHz microwave generator at an input microwave power up to 17 kW and the gas temperature is determined from the rotational distribution of the G ¹Σ_g⁺ excited state of H₂(T(G)). In continuous discharge, the rotational temperature T(G) of H₂(G ¹Σ_g⁺) is found to be nearly equal to the gas temperature determined from rotational distribution of the a³Π_u metastable state of C₂ molecule obtained from absorption spectroscopy. The time evolution of H₂(G ¹Σ_g⁺) rotational distribution in pulsed discharges reaches a Boltzmann equilibrium only 100 μs after the beginning of the pulse. Variations of the T(G) in-pulse value as a function of pressure, volumetric power density and gas velocity is studied. (author)