a b s t r a c t An inexpensive and non-toxic magnetically responsive biocatalyst was prepared by ferrofluid modification of Saccharomyces cerevisiae cells. The prepared biocatalyst enabled efficient decomposition of hydrogen peroxide (HP) and sucrose conversion, due to the presence of active intracellular catalase and invertase. HP was efficiently decomposed in water solutions up to 2% concentration, leaving very low residual HP concentration after treatment. The biocatalyst was stable; the same catalytic activity was observed after one month storage at 4°C