Natural germanium and selenium consist of, respectively, five and six stable isotopes. Several of these isotopes have considerable abundances and one should expect to observe the bands of at least six isotopic variants of germanium monoselenide (GeSe). In this paper, for the first time, the results of the high-resolution electronic spectrum of the main transition A¹Õ -X¹S⁺ of the specific isotopomer ⁷⁴Ge⁸⁰Se, excited in a microwave discharge and recorded in the 33 500-26 000 cm^-1 region using a Fourier transform spectrometer, is discussed. From the rotational analysis of 25 bands involving v´´ = 0-12 and v´ = 0-7, accurate vibrational and rotational constants of the A¹Î state are determined. The present study has revealed perturbations in the v´  = 6 and 7 levels of the A¹Õ state.