Benzo[h]quinoline was used to study the mutagenic activities of benzo[f]quinoline, benzo[h]quinolone and a number of their derivatives in strain TA 100 ofSalmonella typhimurium. It was used in determination of nitrogen-containing polynuclear aromatic hydrocarbons in the gaseous products of the thermal degradation of polymers by HPLC- fluorescence detection. It was used as starting reagent for the synthesis of osmium and ruthenium complexes containing anN-heterocyclic carbene ligand.