The diploma thesis deals with two explosive hybrid mixtures and the evaluation of the optimal formula for calculating the lower explosive limit of these hybrid mixtures. The aim is to theoretically determine the lower explosive limit of hybrid mixtures, where the first hybrid mixture is formed by corn powder with methane and the second hybrid mixture is formed by lucerne powder and methane. Using the graph of Le Chatelier, Bartknecht and Jiang model, we evaluated which curve and the related formula with the LEL calculation is optimal for a given hybrid mixture. For both hybrid mixtures, the optimal and safest curve was found to be the Jiang curve, which means that even the safest relationship for calculating the lower explosive limit is the Jiang relationship. Using Le Chatelier and Bartknecht relationships is less secure. The results were compared with the results of foreign work, where a hybrid mixture of methane and coal dust was investigated. It follows that all three models are useful and practical for determining the LEL of hybrid mixtures.