A standard 20 L spherical chamber was used to study the explosibility of hybrid mixtures systematically. Four different hybrid mixtures, which were composed of two different flammable gases (methane and ethylene) and two different flammable organic dusts (lycopodium and polyethylene), were selected. The maximum explosion pressure P-ex and the maximum explosion rate of pressure rise (dP/dt)(ex) of the four different hybrid mixtures were measured under initial high turbulence conditions over a wide range of composition concentrations (volume concentration y for gas and mass concentration c for dust). Explosion behaviours of the four different hybrid mixtures were analysed and compared with each other. Experimental results have shown that adding different flammable gases to the same dust cloud can all increase the explosion severity of the dust. However, the increase is almost equivalent when different flammable gases with the same equivalent ratio at low values are added. Only if the equivalent ratio is sufficiently higher can a higher increase in the explosion severity be induced by the more explosible gas. Adding the same flammable gas to different dust clouds clearly increases the explosion severity of all these dusts, but the increased ratios of P-max and (dP/dt)(max) are higher for the less explosible dusts, indicating that the influence of flammable gas on the explosion severity is more pronounced for less explosible dusts. (C) 2017 Elsevier B.V. All rights reserved.