The Raman spectra of the Q branches of the nu(1) + nu(2)-nu(2) band of (C2H2)-C-12 and of the nu(1) + nu(2)-nu(2) and 2 nu(2) + 2 nu(5)-nu(2) bands of (C2H2)-C-13 were recorded at high resolution in the gaseous phase. To obtain the spectra a two-step pump/probe technique was used. In the first step, molecules were pumped from the ground to the upsilon(2) = 1 excited state by means of a double pulsed stimulated Raman process. Then, spectra corresponding to the transitions from this state to higher ones are recorded by means of a high resolution quasicontinuous stimulated Raman process. The analysis of the experimental data, taking into account the fourth-order anharmonic interaction coupling the excited states for the C-13 isotopomer, provided unperturbed values for the rotational and distortion constants of the excited states and for the band origins. Accurate values for the x(12)(0) anharmonicity constant have been calculated directly from the energies of the upsilon(1) = upsilon(2) = 1 states for the first time.