This experiment aims at studying the magnetic behaviour of the molecular square complex {[Fe{B(pz)_4}(CN)_3]_2[Co(bik)_2]_2}(ClO_4)_2 . 3H_2O [B(pz)_4 = tetrapyrazolylborate, and bik = bis(1-methylimidazol-2-yl)ketone], and the local features of its photomagnetism. The study will be performed in LF and ZF, following the temperature dependence of the MuSR signal to (i) extract the local exchange interaction in the paramagnetic phase, (ii) clarify a possible phase transition to a ferromagnetic state, and (iii) investigate the local features of the charge transfer processes associated with the photoinduced diapara transitions.The current experiment represents the beginning of a new line of investigation of the Coimbra group, building on its muon expertise and the materials expertise of a group from the Université Pierre et Marie Curie (Paris).