Based on the study of the structures of the known organic reagents for bismuth detection, it is suspected that the functional group responsible for the reaction with bismuth ion is merely the mercapto-group. Thus, the reagent properties of simple thiophenols are studied. A two percent solution of p-dimercaptobenzene in ethyl alcohol gives a yellowish orange spot with bismuth ions by means of spot test techniques. Mercuric, mercurous, silver, lead and nitrite ions interfere. Limit of identification: 3 gamma.. Concentration limit:1:17,000. Although it is not sensitive enough to be used as a reagent in spot test, this result indicates that a further study on the derivatives of the thiophenols may be valuable.