We present results of thermal lens (TL) and photo luminescence on dimethylsulfoxide solutions of poly(2-methoxyaniline) doped with three different inorganic acids. Both thermal diffusivity and fluorescence quantum efficiency (eta) values for all polymers are very close regardless the inorganic acid doping. TL results were in agreement with those obtained from photoluminescence studies. The eta, for all the polymer solutions, decreased with increasing polymer concentration, indicating that nonradiative processes become significant in higher concentrations. Although polyaniline and poly(2-methoxyaniline) solutions show identical behavior in concentrated solutions, the observed fluorescence quenching for poly(2-methoxyaniline) in diluted samples is higher, indicating its higher aggregation at lower concentrations. (c) 2007 Elsevier B.V. All rights reserved.