Ce-compounds are well known to present very rich physics and exotic electronic ground state due to the competing RKKY, Kondo and crystal field interactions. Recently CeRuPO attracted attention for its ferromagnetic Kondo lattice behaviour. CeRuPO crystallize in the tetragonal ZrCuSiAs-type structure. At ambient pressure CeRuPO exhibits ferromagnetic ordering at TC = 15 K. Interestingly the ferromagnetic TC is suppressed by Fe-doping in CeRuPO and a ferromagnetic quantum critical point has been observed in Ce(Ru1-xFex)PO near x ~ 0.86. We therefore propose to investigate the microscopic nature of the low temperature magnetism in CeRuPO and the effect of Fe substitution (with x=0.86) using muon spin relaxation (μSR) measurements in zero-field (ZF) and small applied longitudinal fields (LF) to understand the nature and dimensionality of the magnetism in these compounds.