Abstract: An innovative polyhouse was developed for production of button mushrooms in hot region of Punjab. Length, width and ridge height of polyhouse was 15, 4 and 4.27 m, respectively. Floor was kept at 1 m below ground level. Roof was thermally insulated whereas walls were ventilated. Heat load analysis of polyhouse was carried out in the study. Polyhouse was equipped with fan-pad system and foggers to attain cooling through evaporative cooling mechanism. Water required to reduce the inside temperature by 10°C was determined as 1.3 liters. Performance of polyhouse was evaluated in terms of attaining the desirable temperature and humidity conditions. Results indicated that on operating the cooling systems, inside temperature and RH during October were 22-27°C and ≥75%, respectively. These conditions were suitable for spawn run. In November polyhouse provided 20-22°C temperature and ≥75% RH. These conditions were suitable for case run and fruiting. Favorable temperatures and RH were achieved during February and March also. Thus, study demonstrated that, in hot region, button mushroom farming may be started in October month and can be carried out till March using polyhouse developed in study.