Ethiopia’s wide range of agro-climatic conditions and soil types make it suitable for the production of diverse verities of fruits including tropical and subtropical fruits, around 47 thousand hectares of land are under fruit production. Fruits contain about 65 to 95 percent of water, and their post-harvest life is determined by how quickly they use up their stored food reserves and how quickly they lose water. But The osmotic behavior of plant organs depends upon the equilibrium between the tendency to lose water during transpiration and ability to draw water into cells. To ensure optimum fruit quality during storage time, the temperature and humidity of the conditioned air within storage facility must be precisely controlled by air humidifiers, to reestablish the optimum level of humidity level and cool temperatures of the air surrounding the produce by releasing a fine water mist into the fruits deck. In this study, the effect of mist particle size and concentration on the humidification potential and postharvest quality of fruits (banana, orange, avocado, and mango) was investigated under two kinds of mist-producing humidifiers during 7 consecutive days. Mists generated by ultrasonic humidifier with a droplet size of 1µm-10µm and mist nozzle humidifier with a droplet diameter of 100µm-200µm. The results showed that the cumulative weight loss rate of all samples stored under ultrasonic, nozzle mist, and open-air environment for seven-day trial were 2.22%, 3.43%, and 15% respectively. The maximum temperature drop recorded for nozzle mist humidifier was 4℃ from the ambient of 23℃ and 5.3℃ from an ambient of 25.7℃ for ultrasonic humidifier. And finally, the maximum saturation efficiency achieved by ultrasonic and nozzle mist humidifiers was 0.8967% and 0.8247% respectively.