The assessment of the explosion hazard of a combustible gas mixture is not a trivial task if the type of combustible gases is not known precisely. In this paper, a methodology for assessing the degree of the explosiveness of hydrocarbon gases combined with hydrogen is proposed. The methodology does not require the identification of the type of hydrocarbons, their quantity and concentration. The methodology proposed in this work is based on the measurement of heat released during mixture burning in the catalytic sensor chamber. A multi-stage heating profile with different duration and voltage amplitude was developed to heat the sensor and conduct measurements. This allowed for dividing the catalytic sensor response into hydrogen and hydrocarbons mixture. The measurements were carried out for three-component mixtures of explosive gases (propane, butane and hydrogen) in air. The obtained results demonstrate a good agreement between the experimental results and the theoretical values.