Reactions of peri-hydroxyacenaphthaldehyde and its O-methyl derivative with amines, aryl methyl ketones, and malononitrile gave the corresponding Schiff bases, chalcones, and arylidenemalononitrile. The latter underwent heterocyclization on heating in trifluoroacetic acid to produce 2-oxoacenaphtho[5,6-bc]-oxepine-3-carbonitrile. The condensation of 5-acetyl-6-hydroxyacenaphthene with aromatic aldehydes afforded chalcones, their mixtures with heterocyclization products, or 2-arylacenaphtho[5,6-bc]oxepin-4-one, depending on the substituent in the aromatic ring.