The radical p-NCC6F4CNSSN, 1, can be obtained in two different phases depending upon sublimation conditions. The alpha-phase, 1 alpha, crystallises in space group P (1) over bar, and the molecules are related through an inversion centre. The beta-phase, 1 beta, crystallises in the orthorhombic space group Fdd2 and the molecules are not related by an inversion centre. The latter shows a sharp rise in the magnetic susceptibility at 36K which is accompanied by an out-of-phase component in the a.c. susceptibility. Heat capacity measurements show a distinct peak at 35.5K indicative of the long range ordering of the magnetic moments. The magnetic ordering of the compound is also confirmed by neutron diffraction experiments. Magnetisation isotherms indicate the presence of a small residual moment that saturates below 100 Oe. Extrapolation of the residual moment at T = 0K gives a value for the spontaneous magnetisation of 1.5 x 10(-3) mu(B)/molecule. The behaviour is interpreted in terms of weak ferromagnetism.