Abstract The computer program SEAC is designed to elucidate the structure of organic compounds comprising C (up to 40 C atoms in a molecule), H, N, O, S, Cl, Br and/or I atoms. Artificial intelligence techniques are exploited for empirical interpretation of spectralstructural correlations obtained directly from i.r., 1 H-n.m.r. and u.v. spectra. SEAC works on five levels depending on the entropy of the information input on tested molecules. The computer prints out a set of alternative substructures (levels I–IV) or a set of complete structures which are consonant with the input data.