  We prepared polycrystalline samples of R$_2$PdO$_4$ (R = La, Nd, Sm and Gd)
using a NaCl-flux technique. The measured resistivity is of the order of
10$^3-10^4$ $\Omega$cm at room temperature, which is two orders of magnitude
smaller than the values reported so far. We further studied the substitution
effects of Ce for Nd in Nd$_{1.9}$Ce$_{0.1}$PdO$_4$, where the substituted Ce
decreases the resistivity and the magnitude of the thermopower. The activation
energy gap of 70-80 meV and the effective mass of 15 evaluated from the
measured data are suitable for thermoelectric materials, but the mobility of
10$^{-6}$ cm$^2$/Vs is much lower than a typical value of 1-10 cm$^2$/Vs for
other thermoelectric oxides.
