Exothermic reactions in liquid phase are often performed in a batch reactor with cooling. To avoid runaway, suitable conditions of the reaction and its performance must be selected. It is shown that in the case of liquid phase reactions these conditions should not be determined by the Semenov criterion but by its extension, the sensitivity, which regards the concentration dependency of the reaction. The theoretical relationships are derived on the basis of the heat and mass balances. The results are illustrated by numerical calculations.