Abstract: The principal assumptions about equivalence and energy distribution of the asdorption sites on solidsurfaces used by Langmuir for deriving the equation of monomolecular adsorption are generalized and anew physical adsorption model is proposed and tested with experimental data published in literature.Themodels of Langmuir,Freundlich,Temkin etc.are only the special cases.Assuming uniform density distributionof adsorption energy,the isotherm equation is given asn=K.1n[1+(b_op)~(1/M)or n=K.1n[1+(b_oC)~(1/M)]where n is the amount of adsorption per unit weight or area of solid p or C is tbe pressure of gas or the concen-tration of solution respectively.K,b_o,M are constants with physical meanings as described in this paper.This equation can be used over wide range to quantitatively represent the five types of physical adsorptionclassified by Brunauer.