Thiophene containing water-soluble oligomers were synthesized and characterized. The photophysical properties of these compounds were studied; transient absorption spectroscopy was used to probe the triplet excited state and their ability to sensitize singlet oxygen was spectroscopically monitored in deuterated methanol. The above compounds were tested for their light activated biocidal properties against S. aureus both under UV and visible radiation. Among the oligomers studied, the terthiophene derivative was found to kill the bacteria efficiently.