Aqueous surfactant solutions are used in engineering systems for improving boiling heat transfer. The purpose of this research is to determine the viscosities of surfactant solutions and to investigate the effect of composition on viscosity. The results obtained can possibly be used as reference for further study in the effects of surfactant solution viscosities on nucleate boiling. A rotational viscometer was used to determine the viscosities of three surfactant solutions – SLS, EH-14, and SA-9 – of various compositions at room temperature. It was discovered that the viscosities of SLS, EH-14, and SA-9 had a nearly consistent pattern as their compositions increased. The approximate maximum viscosity measured was 1.39 mPa.s for SLS, 1.52 mPa.s for EH-14, and 3.17 mPa.s for SA-9. Based on the results, it was inferred that as the composition of these surfactant increases, so does the viscosity of the solution
