Chemical composition of photospheres in RS CVn stars

In order to investigate how magnetic activity influences a stellar evolution, we undertake a detailed study of photospheric abundances in a sample of RS CVn stars. Using the Nordic Optical Telescope we investigate abundances of more than 20 chemical elements, including carbon isotopes, nitrogen and other mixing-sensitive species. In this presentation we report on current results of the analysis, among which there are first evidences that extra-mixing processes may start acting in low-mass chromospherically active stars below a bump of the luminosity function of red giants.