The strain rate dependence of the stress‐inducedt–mtransformation behavior of a Ce‐TZP ceramic with a grain size of 1.1 μm has been investigated both in four‐point bend and Charpy impact tests. The crosshead speed was varied from 8.3 × 10−8m/s to 8.3 × 10−3m/s in the four‐point bend tests. In the impact tests, the striking velocity was 2.5 m/s. Double notches (a/w= 0.5) were made on one side of the specimen to measure the stress‐inducedt–mtransformation zone size at the nonpropagated notch tip. It was found that a transition of the transformation zone size with crosshead speed occurred at about 10−6to 10−5m/s. Above this critical speed, the transformation zone was at least an order of magnitude larger in size. This new strain‐rate‐dependent transformation behavior has