Recent observations provide determinations of individual masses , chemical composition and metallicity of the components of the spectroscopic and interferometric binary \iota Peg ( Boden et al . [ 1998 ] ) . Using updated physics , to calibrate the system , we have computed using the stellar evolutionary code CESAM ( Morel [ 1997 ] ) , evolutionary sequences of stellar models with the masses of \iota Peg A 1.326 M _ { \odot } and \iota Peg B 0.819 M _ { \odot } ( Boden et al . loc . cit ) and with different values of the mixing-length parameter \alpha , the helium Y and the heavy element Z initial mass fraction with the constraint of the observed metallicity . Adopting effective temperatures and luminosities , as derived from observations with the bolometric corrections , and the empirical scale of temperatures of Alonso et al . ( [ 1995 ] , [ 1996 ] ) , we find \alpha _ { A } = 1.46 , \alpha _ { B } = 1.36 , Y = 0.278 , Z = 0.017 . The evolution time , including pre-main sequence , is found within \sim 40 { My } \la t _ { ev } \la 0.5 { Gy } . The calibrated models of \iota Peg . A and B are non homogeneous zero age main sequence stars with the evolutionary time t _ { ev } = 56 My . Due to the large uncertainties of their determinations , the values derived for the mixing-length parameters are smaller than the solar one but however marginally compatible with it . Our results ought to be improved as soon as a more accurate value of the magnitude difference in the V filter will be available . Detailed spectroscopic analysis for both components looks practicable , so it is urgently needed .