The amenability of sulfate reduction at low temperature for the treatment of acid mine drainage in arctic areas was investigated with three reactor experiments. The aim of these studies was to assess the potential and determine rates of sulfate reduction at 9oC with formic acid and hydrogen as electron donors. Three different bench-scale reactor configurations were tested: fluidized-bed reactor, membrane bioreactor and gas-lift bioreactor. The reactors were inoculated with a low temperature enrichment culture of sulfate-reducing bacteria. The temperature range of sulfate reduction was studied with a temperature gradient assay. The microbial community structure of the reactors was analyzed using polymerase chain reaction - denaturating gel gradient electrophoresis (PCR-DGGE) with universal 16S rRNA gene primers and SRB specific dsrB primers. The stable sulfate reduction rates at 9oC in all the reactors ranged from 0.6 to 1.4 g SO42- L-1 d-1. The temperature gradient assay supported also by the PCR-DGGE sequence profiling indicated that the low temperature enrichment was dominated by a psychrotolerant mesophilic Desulfomicrobium sp. having their maximal sulfide production rate at 31oC.