A process for photochemical stabilization of non-dyed and dyed polyamide fibre material and mixtures thereof with other fibres which comprises treating the fibre material with a fibre-reactive copper complex of bisazomethines prepared from, for example, salicylaldehydes and aliphatic diamines is described. Some of these copper complexes used are novel compounds. The polyamide fibre material, for example textile material, thus treated largely retains its extensibility and elasticity even after relatively prolonged exposure to light. In addition, a clear improvement in light-fastness is achieved in dyed material by treatment with the metal complex.