The influence of oxygen content on the structural and magnetic properties of the layered Co-based perovskites PrBaCo2O5+δ (0.16<δ<0.80) was investigated by means of both X-ray diffraction and bulk magnetic measurements. An antiferromagnetic state is found for δ<0.35 compounds. For the samples with an oxygen stoichiometry δ=0.5, a strong competition between ferro- and antiferromagnetic states exists in a narrow temperature range 180<T<250K. For δ∈[0.35–0.7], the temperature and field dependencies of the magnetization measurements point toward the appearance of a cluster-glass, in which oxygen-rich and oxygen-poor clusters coexist. The long-range ferromagnetic order, observed for larger oxygen contents (δ>0.7), could thus be arising from the percolation of oxygen-rich ferromagnetic clusters.