Significant areas of temperate bogs have been damaged by peat harvesting. After abandonment and spontaneous regeneration, these secondary mires can become important methane sources towards the atmosphere (Basiliko et al., 2007). Recent studies have shown the importance of methane oxidising bacteria (MOBs) for the recycling of carbon from methane effluxes (e.g., Dedysh et al., 2001; Raghoebarsing et al., 2005) but very little information has been gathered on the ecology of these climatically important organisms along regeneration gradients (Artz et al., 2007). The relationship between MOBs and the conditions found in typical regeneration stages was investigated at four European peatlands (CH, F, UK, FIN), each with up to five sites representing a gradient of natural regeneration stages. These sites were extensively characterized with physico-chemical and plant biological descriptors. With help of refined 16 rRNA fluorescent in-situ hybridisation techniques we quantified the number of various types of MOBs (Type I, Type II, AcidM181) living between 5 and 10 cm below the active Sphagnum carpet. The main axes of explained variance were also compared to methane effluxes. The restricted multivariate analyses show that next to important physico-chemical explanations there is a clear correlation between the time since abandonment of the peat cutting (TAPC) and the various functional groups of active MOBs. For exemple, the type I MOBs were negatively - while type II MOBs were positively - related to time. The AcidM181 MOBs show no significant relationship to time. These different strategies in the ecology of MOBs could have important implications for the oxidation of the effusing methane in this particular type of restoration management practice.