Castor bean plant (Ricinus communis L.) is a very important crop worldwide because it can be produced under severe climate conditions. Also, it gained importance last year because of the increasing industrial demand of biodiesel. The objective of this study was to study the effect of the pH (10, 11 and 12) of extraction of proteins from castor bean cake on some physical properties of films based on these proteins modified by tannin. Increasing pH improved the protein extraction yield without affecting their amino acid profile. The films prepared using these proteins by casting process showed a structural matrix sufficiently cohesive, intense total color difference (δ. E*. = 83-85) and relatively high opacity (8-15%). The values of tensile strength, elongation at break, Young Modulus, water vapor permeability and hydrophobicity of films were affected by the protein extraction pH. 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