We report thermoelectric, magnetic and structural properties of the so-called Kondo semiconductor CeRhAs. The resistivity \rho (T) along the three principal axes exhibits step-like anomalies at T₁ = 370, T₂ = 235 and T₃ = 165 K, respectively, and increases by two orders of magnitude on cooling to 1.5 K. Below T₁ an abrupt drop in the magnetic susceptibility along all the axes is associated with the cell doubling along the b- and c-axes, suggesting a charge-density-wave transition. Below T₃ the increase in the thermopower is strongest along the a-axis with a maximum of 186 \mu V/K at 35 K. The thermoelectric figure of merit becomes largest along the c-axis with the maximum value of 1.0\times 10^-3/K, being comparable with that of CePd₃.

PACS numbers: 75.30.Mb, 71.27.+a, 72.15.Jf