Enzymatic, active oxygen-releasing mixtures may be used as oxidising agents for preparing chemical compounds and in bleaching, washing, cleaning and disinfecting agents. According to the invention the mixture contains oxidoreductase with an α/β-hydrolase fold and a catalytic triad consisting of aminoacids serine, histidine and aspartic acid, a peroxide source, and an aqueous solution of an organic acid or its salt. In order to produce organic peracids, organic acids or their salts in an aqueous solution are converted into organic peracids in the presence of oxidoreductase with an α/β-hydrolase fold and a catalytic triad consisting of aminoacids serine, histidine and aspartic acid, and hydrogen peroxide or peroxide compounds, at a pH value from 3.5 to 6.0 and temperatures from 15 to 80 °C.