Here we report the synthesis, structure and porous properties of a 3D pillared-layer porous framework of Mn(ii)-Mn(iii), {[Mn3(bipy)3(H2O)4][Mn(CN)6]2·2(bipy)·4H2O}n (1). The guest-removed framework (1a) shows significant uptake of C2H2, whereas it excludes the other two C2 hydrocarbons (C2H4 and C2H6). Furthermore, excellent separation proficiency for C2H2 from a mixture of C2H2 and C2H4 (1 : 99, v/v) is realized in a breakthrough column experiment under ambient conditions.