  We present the results of muon-spin relaxation measurements on ferromagnetic
BiMnO3. Below T_C=98.0(1) K oscillations in the time-dependence of the muon
polarization are observed, characteristic of a quasistatic magnetic field at a
single muon site, allowing us to probe the critical behaviour associated with
the magnetic phase transition. We are able to suggest candidate muon sites on
the basis of dipole field calculations. Close to T_C, fluctuations of the Mn^3+
moments are characteristic of critical behaviour while there is a sharp
crossover to a region of fast dynamic fluctuations at higher temperatures.
