Benzimidazolo benzothiophene derivatives were prepared by liquid phase combinatorial synthesis using soluble polymer support PEG 5000 and 4-fluoro-3-nitrobenzoic acid as starting materials with substituted primary amines. All these synthesized compounds were established by the spectral data and tested for antimicrobial activity against gram positive bacteria, i.e. S. aureus, B. subtilis and gram negative bacteria, E.coli and P.aeruginosa and anti fungal activity against C. albicans. Ampicillin and ciprofloxacin were used as standard for antibacterial activity and cotrimoxazole for anti fungal activity. Compared with standards compounds (1a-h) showed significant activity against bacterial species and 1g showed significant activity against fungal species.