  Physical parameters of galaxies (as luminosity, stellar mass, age) are often
derived by means of the model templates which best fit their
spectro-photometric data. We have performed a quantitative test aimed at
exploring the ability of this procedure in recovering the physical parameters
of early-type galaxies at 1<z<2. A wide range of simulated SEDs, reproducing
those of early-type galaxies at 1<z<2 with assigned age and mass, are used to
build mock photometric catalogs with wavelength coverage and photometric
uncertainties similar to those of two topical surveys (i.e. VVDS and GOODS).
The best fitting analysis of the simulated photometric data allows to study the
differences among the recovered parameters and the input ones. Results indicate
that the stellar masses measured by means of optical bands are affected by
larger uncertainties with respect to those obtained from near-IR bands, and
they frequently underestimate the real values. The M/L ratio in the V band
results strongly underestimated, even when derived from the recently proposed
recipe based on rest-frame optical colours (e.g. (B-V)).
