This work models a passive method of cooling the body to increase the work periods in hot environment. Cooling is performed by wearing a cooling vest containing packages of phase change materials (PCM) made of salt mixtures that melt at a fixed temperature to prevent increase in skin temperature thus maintaining comfort. A dynamic mathematical model of the heat and moisture transport in clothing layers with PCM material is developed. The fabric-PCM model is validated by experiment on clothed heated cylinder in wind tunnel under controlled environment. The internal air layers confined between the PCM and the heated cylinder (microclimate air) and between the PCM and the outer clothing (macroclimate air) are measured. Good agreement is found between experimental temperatures and predicted values by the fabric-PCM model with maximum errors of 4.5% and 2.5 % respectively.