EXHIBIT NO. 21 SUBSIDIARIES OF NUI CORPORATION NUI Capital Corporation (a Florida corporation), formerly Essel Corporation, Utility Billing Services, Inc. (a New Jersey corporation) and NUI Environmental Group, Inc. (a New Jersey Corporation) are wholly -owned subsidiaries of NUI Corporation. NUI Energy, Inc. (a Delaware corporation), formerly Natural Gas Services, Inc., and NUI Energy Brokers, Inc. (a Delaware Corporation) are wholly-owned subsidiaries of NUI Capital Corporation.