It has been shown that the use of neutron reflection from magnetically non-collinear media allows to determine the local (averaged over the region coherently illuminated by the neutron) and the mean magnetic induction, the mean square direction cosines of the local magnetic induction of thin ( ∼ 10-500 nm) films. Thus, polarised neutron reflectometry (PNR) can be used to study magnetic properties of such films, when the use of the transmission depolarisation technique is problematic. The first two Fourier transform coefficients of the angular distribution function of the domain magnetisation can be found in zero field. Small-angle scattering at domains under reflection has been used to evaluate the mean domain size. The study of magnetisation processes in a Fe₃₆Co₆₄ (170 ± 3 nm) film has been undertaken to demonstrate the new possibilities of PNR. Rotation of the polarisation vector under neutron reflection has been observed.