A toner for developing electrostatic images is prepared from a binder resin and a hydrocarbon wax. The toner is provided with improved fixability and anti-offset characteristic by controlling the thermal characteristic of the hydrocarbon wax so as to provide a DSC (differential scanning calorimeter) curve, showing an onset temperature of heat absorption in the range of 50.degree.-110.degree. C. and at least one heat absorption peak P1 in the range of 70.degree.-130.degree. C. giving a peak temperature T.sub.P1 on temperature increase, and showing a maximum heat evolution peak temperature in the range of T.sub.P1 .+-.9.degree. C. on temperature decrease. Correspondingly, the toner provides a DSC curve showing a rising temperature of heat absorption of at least 80.degree. C., an onset temperature of heat absorption of at most 105.degree. C. and a heat absorption peak temperature in the range of 100.degree.-120.degree. C., respectively on temperature increase, and showing a heat evolution peak temperature in the range of 62.degree.-75.degree. C. and a heat evolution peak intensity ratio of at least 5.times.10.sup.-3 on temperature decrease.