Mechanism of the condensation reactions of methylglyoxal, phenylglyoxal and benzoylacetaldehyde with phenolic compounds have been discussed. It was observed that the reaction mechanisms changed depending on the type of the phenolic and also dicarbonyl compounds. While, methylglyoxal gave the angular methyl derivative of naphthofuraranonaphthofuran with 2-naphthol, phenylglyoxal and its p-chloro and p-methoxy derivatives formed benzo[b]naphtho [2,1-f]oxepine-13-ones. However, resorcinol behaved different and gave 2-phenyl-3-(2,4-dihydroxy)-6-hydroxy-benzo[b]furans with phenylglyoxal derivatives. 2-Phenyl-4-(2-hydroxynaphthyl)-4H-naphtho[b]pyran was produced from the reaction of benzoylacetaldehyde and 2-naphthol, but the reaction product was 3,9-dihydroxy-6-phenyl-6,12-methano-12H-dibenzo[1,3]dioxocin when the same carbonyl compound reacted with resorcinol.