The evoked dynamics of the omega potential and its relation to some parameters of mental working capacity in operators working at steam power plants were studied under production conditions. The dependence of the omegagram type on the background level of the omega potential was determined. 12 types of omegagrams constituting two A and B clusters with negative correlation were distinguished. The highest level of mental working capacity was observed in operators with the background values of the omega potential not exceeding 45 mV and with the omegagram type belonging to the B cluster.