The invention relates to a liquid bleaching composition for catalytically bleaching substrates, especially laundry fabrics, with atmospheric oxygen or air. A liquid bleaching composition is provided comprising an organic substance which forms a complex with a transition metal, the complex catalysing bleaching of a substrate by atmospheric oxygen, and a liquid carrier or solvent, wherein the composition is substantially devoid of peroxygen bleach or a peroxy-based or -generating bleach system. Also provided is a method of bleaching a substrate comprising applying the liquid bleaching composition to the substrate. Also provided is a method of treating a textile by contacting the textile with the liquid bleaching composition, whereby the complex catalyses bleaching of the textile by atmospheric oxygen after the treatment.