  We study the thermodynamic properties of massless Dirac fermions in graphene
subjected to a uniform magnetic field $B$ together with Rashba coupling
parameter $\lambda_R$. The thermodynamic functions such as the Helmholtz free
energy, total energy, entropy and heat capacity are obtained in the high
temperature regime using an approach based on the zeta function. These
functions will be numerically examined by considering two cases related to
$\lambda_R$ smaller or greater than $B$. In particular, we show that the
Dulong-Petit law is verified for both cases.
