The reduction of microbial load in olives is significant in terms of food safety and shelf life. The processes applied in olive production can vary from country to country and according to the type of olives. During the conventional production process of olives, a thin layer formed mainly by moulds such as Penicillium and Aspergillus is observed on the surface of the brine. Two Penicillium species, P. citrinum and P. crustosum, and two Aspergillus species, A. niger and A. versicolor were inoculated on black olives and after incubation, microwave-treated for different time periods (30, 60, 120, 180, 240 and 300 seconds). Comparison of mould counts before and after each treatment suggested that microwave treatment for 180, 240 and 300 seconds was effective in reducing the mould count and increasing shelf life. The highest inhibition for all mould strains was observed at 300 seconds.