Abstract: Heat transfer of supercritical water in a 2×2 rod bundle with wrapped wire and two channels was investigated experimentally. The non-uniformity of circumferential wall temperature distribution in heating rods was observed. The heat transfer deterioration (HTD) occurred at low G/q in whole rod bundle region while the secondary HTD was observed close to the upstream. The HTD at downstream was restrained due to the disturbance of wrapped wire. The studies show that the heat transfer behavior is similar to that in single tube. The correlation of Bishop et al. (1964) gives the best prediction of Nusselt number. Compared with a 2×2 bare rod bundle, the wrapped wire strengthens heat transfer.