A functional model based on adsorption pattern suggested by Langmuir was proposed to explain the effect of initial cellulases concentration (E0) on the concentration of cellulases adsorbed (Ea). A number of experiments (triplicates) were conducted to determine the equilibrium adsorption values for various E0's (125, 141, 163, 183, 220, 250, 262 μg mL-1). The maximum Ea for the E0 of 262 μg mL-1 was around 117 μg mL-1. Langmuir model predicted Ea as 99.29 μg mL-1 and the response surface methodology (RSM) Model predicted it as 109.30 μg mL-1 while the experimental value of Ea was 107.70 for an E0 of 183. The proposed predictive RSM model for adsorption provided less percent error (i.e. 0.2) than the Langmuirian model, hence, RSM was used to develop a model for desorption of cellulases from Avicel. The variables considered for desorption of cellulases NS 50013 were temperature (40, 50, 60 oC), pH (7, 8 and 9) and cellulases adsorbed (Ed) from E0. The proposed desorption model was validated for E0 values of 175 μg mL-1, 190 μg mL-1, and 210 μg mL-1. The error between the predicted and experimental values of Ed was around 4-8% for E0 values of 175 to 210 μg mL-1. The cellulases desorption model is first time presented. The cellulases desorption model will bring certainty in estimation for the amount of cellulases to recycle and corresponding reduction in the initial cellulases loading and hence decrease in bioethanol production price.