Thermally treated peat is known to be a prospective sorbent for oil removal. The used oil spill clean-up sorbents could be further reused for a few cycles, if an appropriate treatment is undertaken. In this study, a 36 days biodegradation batch experiment was performed with oil-degrading bacteria consortium MDK.EKO-7 and a peat sorbent (PeatOS) contaminated with diesel or raw oil. FDA hydrolysis, urease and dehydrogenase activity, as well as the concentration of hydrocarbons were measured in a peat-slurry system. Biodegradation of hydrocarbons up to 90 % was detected in the set with 2% (w/w) diesel-oil contaminated peat. The measured enzymes behaved differently over time. The peat sorbent (PeatOS) contaminated by raw oil with concentration 5mg/g dw, inhibited growth of bacteria consortium. Addition of nitrogen and plant extract to a peat-slurry with 2% diesel resulted in a significant (p<0.05) increase of FDA hydrolysis and urease activity after 36 days' incubation. The results obtained in this study, indicate that a recovery of the used oil-spilled peat sorbent is possible. Further experiments will be performed in order to optimise biodegradation conditions, using nutrients and surfactants.