  We present a high-temperature expansion (HTE) of the magnetic susceptibility
and specific heat data of Melzi et al. on Li2VOSiO4 [Phys. Rev. B 64, 024409
(2001)]. The data are very well reproduced by the J1-J2 Heisenberg model on the
square lattice with exchange energies J1=1.25+-0.5 K and J2=5.95+-0.2 K. The
maximum of the specific heat Cv^{max}(T_{max}) is obtained as a function J2/J1
from an improved method based on HTE.
