  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, evolutionary sequences of stellar models with the masses of \iota Peg A
  1.326 Msol and iota Peg B 0.819 Msol (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 40 My < t_ev < 0.5Gy. 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.
