We have successfully grown an arsenopyrite marcasite type RhSb2 single crystal, and systematically investigated its crystal structure, electrical transport, magnetic susceptibility, heat capacity, and thermodynamic properties. We found that the temperature-dependent resistivity exhibits a bad metal behavior with a board peak around 200 K. The magnetic sus-ceptibility of RhSb2 shows diamagnetism from 300 K to 2 K. The low-temperature specific heat shows a metallic behavior with a quite small electronic specific-heat coefficient. No phase transition is observed in both specific heat and magnetic susceptibility data. The Hall resistivity measurements show that the conduction carriers are dominated by electrons with ne=8.62 × 1018 cm?3 at 2 K, and the electron carrier density increases rapidly above 200 K without change sign. Com-bining with ab-initio band structure calculations, we showed that the unusual peak around 200 K in resistivity is related to the distinct electronic structure of RhSb2. In addition, a large thermopower S(T ) about?140 μV/K is observed around 200 K, which might be useful for future thermoelectric applications.