MUSHROOM quickly loses its quality due to susceptible to browning, degradation of composition and microbial spoilage after harvesting and during marketing. Hydrogen peroxide is classified as generally regarded as safe for use in food, fruits and vegetables. It could be used for its properties as a bleaching and antimicrobial agent. The quality evaluation was studied during storage of fresh white button mushroom (Agaricusbisporus). Mushrooms were immersed after harvesting in 1, 2 or 4% of hydrogen peroxide comparing to immerse in water (control). The results showed that hydrogen peroxide treatments were effective for keeping eating quality, nutritional value, sensory attributes and microbial safety during storage due to decrease the degradation in colour, composition and hardness as well as reducing weight loss and microbial load. At the end of storage period, 2% H2O2 decreased browning index by 45%, relative membrane permeability by 24% and weight loss by 15% compared to the control. Immersing mushrooms in 2% H2O2 also increased whiteness, dry matter, total soluble solids, protein and hardness. Lower molds and yeasts count by 23% and total bacterial count by 21% than the control were obtained. The sensory evaluation at the end of storage period indicated that 2% H2O2 treatment had better colour, texture and general acceptance than the control.