In our previous study, effect of heat treatment on corrosion resistance performance of Ni, Ni84Cr16, HRA2 and HRC1 alloys was conducted. It was evident from this study that the two high-entropy alloys (HEA), HRA2 and HRC1, gave the best corrosion resistance performance. Corrosion performance of HRA2 alloy was almost the same in furnace cooled (FC) and water quenched (WQ) heat treatment conditions, indicating the stability of the alloy. Despite achieving the excellent performance, a significant difference was observed in HRC1 alloy when exposed in both heat treatment conditions. This difference was attributed to behavior of high amount of Cu contained in the alloy. However, the microstructural analysis were not conducted to verify this view. Thus, the main focus of the current study is to conduct microstructural analysis of HRC1 HEA under FC and WQ condition in an attempt to reveal the cause for difference in corrosion resistance performance. The optical microscopy (OM) and (SEM: EDS) were used for this purpose. Based on SEM-EDS analyses, microstructures of both samples were mainly comprised of areas belonging to FCC matrix, W-Mo rich and small Cr-rich islands. The main difference between the two samples is on the FCC matrix. In the HRC1 FC sample, the matrix is comprised of only FCC Ni-rich solid solution, whereas in the HRC1 WQ sample FCC matrix consists of areas that are Ni-rich and also areas that are Cu-rich. Thus, superior corrosion resistance in HRC 1 WQ sample as compared to HRC1 FC is attributed to the latter.