An exact rear stagnation point solution is sought for a viscous, incompressible conducting fluid in the presence of a magnetic field. It is found that a steady solution exists only if [Nscr ] ≥ 2, where [Nscr ] = σB2/ρα is the interaction parameter of the flow based upon the normal component of the magnetic field at the wall. Here α is a positive rate of strain, which, for a finite body with length l and velocity U0, is of the order of U0/l.

The steady solution is found, and from its existence it is inferred that separation of the viscous boundary layer does not begin at the rear stagnation point when [Nscr ] ≥ 2, and that such separation can be prevented. This supports theoretical work by Moreau (1964) and experimental work of Tsinober, Shtern & Shcherbinin (1963).

When [Nscr ] < 2, the flow is necessarily unsteady, and in this case an asymptotic analysis (as t → ∞) similar to that of Proudman & Johnson (1962) is undertaken. For [Nscr ] < 1, the magnetic and non-magnetic flows are qualitatively alike, in that there is a growing inviscid region dominated by eddies, and an ultimately steady layer at the wall representing a viscous forward stagnation point flow.

For 1 < [Nscr ] < 2, the inviscid region again grows with time, but no eddies appear. It is thus suggested that for this range of [Nscr ] separation occurs without reversed flow.