The tribological behavior of TiZrHfNbTa refractory high-entropy alloy (RHEA) sliding against Si3N4 ball was investigated in the air, deionized water and seawater at room temperature as well as under dry condition at high temperature. The results showed that the TiZrHfNbTa RHEA was composed of single BCC phase. The wear rate in air, deionized water and seawater reached the maximum value of 3.02 × 10−4 mm3/(Nm), 2 × 10−4 mm3/(Nm) and 3.18 × 10−4 mm3/(Nm) at 10 N, respectively. Moreover, the wear rate in deionized water was much lower than that in air, while the wear rate in seawater was close to that in air. The wear mechanisms were all transitioned from the abrasive wear to adhesive wear with increasing the normal load. At high temperature, the wear rate increased first and then decreased, reached the maximum value of 2.04 × 10–4 mm3/(Nm) at 500 ℃. In addition, oxidation occurred at 400 ℃. The wear mechanism changed from the abrasive wear to oxidation wear at high temperature. Graphical Abstract