During Military operations, the soldiers are often deployed to hot regions. It is very important to acclimatize them in advance to heat stress to reduce the risk of heat illnesses. The existing heat acclimation protocols require eight to fifteen days. We have attempted to develop a rapid acclimatization schedule with duration of four days. The study was approved from Institutional human ethical committee. Eighteen healthy Military personnel (n=18), age: 25±4 years, height: 172±4cm, weight: 66±3 Kg volunteered to participate in the study. They were informed about the purpose of the study and possible risks and signed a consent form. They were divided into three groups with six volunteers in each group. The volunteers in group I were subjected to a previously standardized acclimation protocol, as per which they were made to perform free hand exercise in human climatic chamber at 45°C and 30% relative humidity for one hour/day for eight days. The volunteers in group II were made to perform free hand exercise in human climatic chamber at 45°C and 30% relative humidity for one hour/day for four days. The volunteers in group III were made to perform free hand exercise in human climatic chamber at 45°C and 30% relative humidity for two hour/day for four days. One hour exercise was performed in the forenoon followed by one hour rest, after which one hour exercise was performed again. For all the three groups of volunteers, the Core Body Temperature (CBT), Mean Skin Temperature (MST) and Mean Body Temperature (MBT) were noted before and after exercise. For individuals of group I, a significant difference was observed in post exercise CBT (37.14 ±0.14 vs 36.82 ±0.14, p<0.05), MST (35.90 ±0.30 vs 35.25 ± 0.23, p<0.05), MBT (36.77 ±0.19 vs 36.35 ±0.17, p<0.01) at eighth day compared to the first day. For individuals of group II, a significant difference was observed in post exercise CBT (37.16 ±0.04 vs 36.64 ±0.06, p<0.01), MST (36.09 ±0.05 vs 35.61 ± 0.11, p<0.05), MBT (36.84 ±0.04 vs 36.21 ±0.11, p<0.05) at fourth day compared to the first day. For individuals of group III, a significant difference was observed in post exercise MBT (36.98 ±0.02 vs 37.06 ±0.02, p<0.05), MST (35.58 ±0.06 vs 35.53 ± 0.10, p<0.05), MBT (36.56 ±0.03 vs 36.46 ±0.02, p<0.05) at fourth day compared to the first day. There was no significant difference between post exercise CBT, MST and MBT of group I at eighth day and group III at fourth day. A significant difference was observed post exercise in CBT (36.82 ±0.14 vs 36.64 ±0.06, p<0.01) MST (35.25 ± 0.23 vs 35.61 ±0.11, p<0.05) MBT (36.35 ±0.17 vs 36.21 ± 0.11, p<0.05) of eighth day of group I and fourth day of group II. We have successfully shortened the duration of acclimation schedule as can be concluded from the data. It will help to minimize the time and manpower losses suffered by Military for acclimation of personnel.