The photocatalytic degradation of methyl orange has been studied under visible light. The combination of polyaniline and montmorillonite doped by cobalt and nickel cations enhanced the photocatalytic activity compared to pristine polyaniline. Kinetic measurements have been tentatively explained on the basis of their composition, electronic structures, structural and textural properties. Separate experiments performed on doped montmorillonites show weak performances, reflecting their insulating behaviour, altered by diffusion limitations. A pseudo-first order agrees with a weak methyl orange adsorption. More open porosity of composite materials led to improved efficiency. Their superiority compared to doped montmorillonites has been preferentially related to surface heterogeneity, stronger methyl orange adsorption and lower band gap energy.