Aims. Known mental and physical capacity of human is one of the important subjects at work physiology. In work physiology, physical work capacity can be determine. In this research, physical, work capacity, maximum aerobic capacity and consummate oxygen of 36 Iranian military men personnel at age between "20-29" can be measurement. Measurement can be at normal and heat humid chamber laboratory clime.

Methods. Perform treadmill model 1160, Digital barometer model MD 10544, Temp sense electronic model MO2, Digital with 100 gr correlation converter. Heart rate measuring model T61 and normal solution serum. The method was used for examinations was Balk method.

Results. The result of this research .show physical work capacity (PWC) in normal and very heat humid clime 3.69 and 3.41 kcal /min respectively .maximum physical capacity (MPC) at two condition , 10.87 and 10.02 kcal/min respectively .although maximum aerobic capacity (VO2 max) at this personnel 29.52 and 28.14 mi/kg/min respectively .average of body surface in normal and very heat humid condition was 1.88 and 1.85 m2 respectively .average length time activity in normal and heat humid is 9.37 and 8.42 min .

Conclusion. compare result of physical work capacity, maximum physical capacity and maximum aerobic capacity this personnel in two normal and heat humid clime condition indicated have a significant different. According international work organization standard this personnel can do light work in their shift work