Objectives The purpose of this study was to assess iron oxidation and prospects of bioleaching at low temperatures relevant in arctic and boreal environments. Iron-oxidizing acidophiles were enriched at 5°C from samples from a Ni-Cu mine site (northern Siberia) and the kinetics of iron oxidation by one of the isolates (strain SS3) was evaluated at low temperatures. Additionally, low temperature bioleaching was tested with either a pure (strain SS3) or mixed (T7 mix) culture in stirred tank reactors and column reactors, respectively. Results The oxidation kinetics at 5°C could be described with the first order rate expression. The rate of iron oxidation at 5°C by SS3 was nearly as fast as that at 30°C by a mesophilic reference strain. Iron precipitates in cultures grown at 5°C were mixtures of schwertmannite and jarosite, whereas jarosite was the exclusive solid phase at 30°C. The bioleaching potential of isolate SS3 was tested in stirred tank reactors containing pyrite, pyrite-arsenopyrite, and chalcopyrite concentrates. With SS3, the leaching rates in stirred tank reactors were much lower at 5°C than at 30°C due to slow chemical oxidation rates of sulfide minerals by Fe