One of the main advantages of laser ignition is the ability to ignite lean combustible mixtures, resulting in obvious economy and reduction of harmful emissions, primarily NOx. Experimental data on exhaust composition are presented in the literature very poorly. As a rule, the studies were not of a systematic nature, considered only very specific conditions of combustible mixtures exposure and composition (mainly methane-air), and were obtained for experimental piston engines, the design and operational features of which could significantly affect the result. We suggested that in order to obtain a starting point for further optimization, a study of exhaust composition should be carried out under conditions of minimal impact of the engine design. For this purpose, an experimental stand was created, which allows to investigate the laser ignition of combustible mixtures of different composition in wide pressures range. We studied the laser ignition of gas mixtures based on butane with fuel-air coefficients ϕ ∼ 0.8 – 1.2, in pressure range p ∼ 1 – 3 bar, ignited by radiation of the the nanosecond Nd:YAG laser. The exhaust composition was analyzed by O2, CH, CO, CO2, NOx. Correspondence of the obtained results known from other experimental and theoretical works is analyzed.