A method for intensifying combustion of gas-fuel mixtures consists of stimulating the combustion mixture in a combustion chamber by a pulsed high-voltage discharge of nanosecond duration, wherein the discharge amplitude is set up according to a condition of maximising a heat input in electronic degrees of freedom and in a gas dissociation and preventing the passage of plasma electrons to an escape mode at a main discharge stage, the high-voltage pulse leading edge build-up time is limited by the condition of obtaining a homogeneous filling of a discharge gap by plasma and a pulsed energy efficient transmission to the plasma, a high-voltage pulse time is limited by the condition, wherein a highly-unstable plasma state is attained, the discharge gap resistance is reduced, the discharge gap is better matched to a generator, and an efficient electric power input into the plasmas is obtained.