Delayed hydride cracking (DHC) tests were conducted on Zr–2.5Nb compact tension (CT) specimens with 60–80ppm H at temperatures ranging from 160 to 280°C in the load increasing mode where the applied stress intensity factor, K I was increased step-wise by 0.5MPam −1/2 from 4.5MPam −1/2 until a crack grew. Critical hydride lengths, l c , corresponding to the spacing of the striation lines, were determined with the applied stress intensity factor, K I from the fracture surfaces of the Zr–2.5Nb CT specimens. The l c was the largest at as low a K I as just above K IH in Stage I and leveled off to 30μm at a larger K I of above 9MPam −1/2 especially at 250°C, corresponding to Stage II. This finding was also observed at all the investigated temperatures. Since DHCV is inversely governed by l c according to Kim's DHC model, it is concluded that the K I dependency of DHCV is caused by the K I dependency of l c . The increased l c in Stage I is suggested to arise from the creep effect on the increased K IH that is experimentally supported by Sagat's results. The rationale for this suggestion is provided using Kim's hypothesis that cracking of hydrides occurs by their interaction with twins.