Hydroxy benzisoxazole 1 was converted into chlorobenzisoxazole 2 and then to hydrazinobenzisoxazole 3. New tricyclic compounds, triazolobenzisoxazole 4 was obtained from hydrazinobenzisoxazole when treated with formic acid. Similarly 3-hydroxytriazolo benzisoxazole 5 and 3-mercaptotriazolobenzisoxazole were prepared by the action of urea and CS2 in alkali respectively. The compounds have been characterized by elemental analysis and spectral data. Newly synthesized compounds have been screened for their antimicrobial activities against several microbes.