Analytically pure selenonyl bis(acetate) SeO2(O2CCH3)2 was prepared by the reaction of SeO3 with a stoichiometric amount of acetic anhydride in nitromethane; it crystallizes in the monoclinic P21/n space group with one molecule in the asymmetric unit and a = 5.2044(1) Å, b = 21.6580(5) Å, c = 6.7074(2) Å, and β = 93.628(2)°. The selenium atom binds to two oxo groups and two acetate anions in a distorted tetrahedral geometry. Analysis of the Hirschfeld surface indicated the presence of numerous C–H···O interactions.