Three series of new 1-(isomeric methyl)benzoyl-3-arylthioureas (1–3a– i) were prepared from 2-, 3-, and 4-methylbenzoyl chlorides via isothiocyanate formation followed by treatment with various substituted anilines. The base-catalyzed condensation of thioureas (1–3a–i) with acetone was carried out in the presence of bromine to afford the corresponding 1-(isomeric methyl) benzoyl-3 aryl-4-methyl-imidazole-2-thiones (4–6a–i) in good yield. Thioureas and the corresponding thiones were characterized by spectroscopic data and elemental analyses. The mass fragmentation pattern of thiones is also discussed. The thiones were evaluated for antibacterial, antifungal, and insecticidal activities and exhibit significant antibacterial activity and slight but not significant antifungal and insecticidal properties.