In previous work, the reverse osmosis (RO) process was evaluated based on the potential synergy of (Process Design and RSM) methodologies, and the effect of membrane age, % recovery, (concentration of salts, pH, temperature, and pressure) of feed water and the rejected brine concentration were optimized and modeled. The current work included the determination of phenomenological parameters of mass transfer for RO membrane systems using Spiegler-Kedem-Katchalsky model. Mass transfer coefficient and membrane permeability for salts were determined as a function of temperature and % recovery. The calculations of mass transfer parameters were based on using a reference RO membrane ESPA4-LD-4040, three stages RO process, 3-year membrane age with 95% and 85% recovery, permeate flow 20 m3/h, pH 7, constant feed TDS 800 mg/l, constant pump pressure for feed water 15 bar, and temperature of feed water 4, 8.2, 25, 30, and 42oC. The results showed that when temperature increases from 4°C to 42°C, the mass transfer coefficient increases by 35.44% for 95% recovery, and 83.97% for 85% recovery respectively. A general mathematical model describing the relation of mass transfer coefficient with feed water temperature, water permeability, and salt permeability was developed. Spiegler-Kedem-Katchalsky model proved its capability for membrane performance evaluation by determination and correlation of the phenomenological parameters of mass transfer for the membrane system.