The explosion features of nicotinic acid dust in atmosphere of methane and air at different concentrations of either dust or gaseous fuel are studied. Experimental measurements of the pressure history, deflagration index and flammability limits are performed by the standard 20 I Siwek bomb though adapted for such hybrid mixtures. Data show non linear effect of explosion severity and the synergistic effects when hybrid mixtures explode. Results allow the definition of five different regimes of the gas/dust/air mixture explosion in the plane dust concentration vs. fuel concentration. (C) 2010 Elsevier B.V. All rights reserved.