The turn-on process and steady state current-voltage characteristics have been investigated in 4H-SiC thyristors with a forward breakover voltage close to 700 V and pulse switch current density of . The current rise constant decreases monotonically with increasing temperature: ns at and ns at T = 500 K at high bias V. The value of ns is the lowest observed value for SiC thyristors. At very high current density the residual voltage drop on 4H-SiC thyristors is lower than on identically rated Si thyristors. The voltage drop decreases monotonically with increasing temperature.