This investigation aimed to determine the suitability of different agro-industrial byproducts from the food industry in the coloniztion of pleurotus ostreatus mycelium. The byproducts used were apple pomace, spent coffee grounds and banana peel. Dry apple pomace was obtained from Eszat Kft. whereas banana peels and spent coffee grounds were obtained directly from the raw materials bought at a local supermarket. Three concentratiosn from each media were tested: 20, 40 and 60 g/L and compared to the standard malt extract agar. The investigation was carried out in the Nano food laboratory of the Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen. The results showed that the different byproducts tested have comparable results to the traditional used culture media in terms of mycelium growth rate and density. Spent coffee grouns (20 g/L) medium showed the fastest mycelial growth rate with a value of 14,40 mm/day, the same as in the control media. The denser mycelium was obtained on the spent coffee grounds medium (60 g/L) with a somewhat dense mycelium.