Infrared, ultraviolet, and nuclear magnetic resonance spectra have been determined for phorone, dibromophorone, bromohydroxyphorone, and some related compounds. Dibromophorone and bromohydroxyphorone show no evidence of ring窶田hain tautomerism. The former (3,5-dibromo-2,6-dimethylhepta-2,5-dien-4-one) exists in a hindered di-(s-cis) conformation.