Experimental investigations of the lower explosion limits (LEL) of three-component hybrid mixtures of six combustible dusts, three gases, and four solvents were performed in the modified Godbert-Greenwald furnace. The test protocol was in accordance with European standard EN 50281-2-1 which is originally used to determine the minimum ignition temperature of dusts. Modification was done on the equipment to test for the explosion limits for dusts, gases, solvents, and hybrid mixtures. In order to prove the validity of our experimental procedure, the LEL for pure gases were initially tested and the results were compared with values found in literature obtained from the standard procedure which show very good agreement. The experimental results demonstrated a significant decrease of the explosion limits of gas, solvent, or dust and an increase in the likelihood of explosion when a small amount of dust was mixed with gas or solvent and vice versa. For example, the minimum explosible concentration (MEC) of high density polyethylene (HDPE) of 174 g/m(3) decreased to 130 g/m(3) upon addition of methane the concentration of which itself was below the LEL. The MEC of HDPE further decreased to 65 g/m(3) when a nonexplosible concentration of hexane was added. (C) 2016 American Institute of Chemical Engineers Process Saf Prog 36: 81-94, 2017