The present invention relates to hair colouring and hair bleaching compositions comprising a first component comprising at least one oxidizing agent and a C6 to C16 alkyl glucoside and a second component comprising an anionic surfactant and a fatty alcohol. The compositions surprisingly provide improved hair colourant and bleaching compositions which deliver lift, lightening and colour, whilst minimizing damage and which provide the required viscosity both pre and post mixing of the first and second components.