The antimicrobial activity of a newly prepared vegetable oil based organotin polymer by the condensation reaction between fattyamide diol (N, N1-bis 2 hydroxy ethyl castor oil fatty amide) and butyltin chloride dihydroxide has been studied against the bacterial species E. coli, S. typhi (Gram-negative), S. subtillis, S. aureus (Gram-positive) and three fungal strains (Candida albicans ATCC-10261, Candida glabrata ATCC-90030, Candida tropicalis ATCC-750). The antifouling property of this polymer has also been investigated. The conventional spectroscopic techniques such as FTIR, 1H-NMR and 13C-NMR have been used to establish the structure of the polymer. The physicochemical characteristics like acid value, hydroxyl value, saponification value, iodine value, specific gravity and viscosity were determined by standard laboratory methods. In addition the thermal stability was analysed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The polymer was found fairly active against the tested microbial species and showed antifouling property.