Dust explosion hazard exists in plants and facilities wherever combustible dusts are handled. Minimum explosible concentration of dust clouds is an important factor requiring special attention for hazard evaluation if any technological equipment is to be protected by inertisation. The mathematical models available far prediction of this parameter have been analysed for their application to organic dust clouds, Solution of the most general model for determination of minimum explosible concentration of dust clouds proposed by Mitsui and Tanaka is presented, together with the comparison with experimental data. It has been found that the model is not successful in predicting the minimum explosible concentration for organic dusts. Recommendations on requirement of development of a new model for prediction of minimum explosible concentration of an organic dust such as polyethylene have been given.