Separation performance was measured for the disc plate and frame type reverse osmosis module using NaCl and sucrose solutions. An analysis of membrane performance was done following the equations proposed by Kimura-Sourirajan[8]. The membrane permeability was $2.17 imes 10^{-6}$(gmol/$cm^2$-sec-bar) and independent of operating pressure. The effect of concentration polarization for sucrose solution was higher than that of NaCl. Permeation flux for sucrose solution above 40 bar was decreased as operating pressure was increased. Solute rejection for NaCl solution was decreased, but that of sucrose was increased as operating pressure was increased.