Two molecular magnetic systems are considered which show low-temperature ordered states. One of them is F4BImNN, a nitronyl nitroxide radical magnet, an excellent realization of a one-dimensional ferromagnet. The other is [Ni(hmp)(chp)Cl]4, a single molecule magnet containing a Ni4 cubane core which has a S=4 ground state. This is believed to order magnetically at low T but which also shows an unprecedentedly large quantum tunnelling rate which is surprisingly unaffected by the onset of magnetic order. The aim of our muon study is to confirm magnetic order in both compounds, to perform a measurement of the internal field distribution in the ordered state, and the probing of the field dependence to gain insight into the nature of the magnetic phase diagram in F4BImNN and the relaxation mechanisms in [Ni(hmp)(chp)Cl]4, comparing results to other nitroxides and SMMs we have obtained.