A new rapid method of counter-flow heat regenerators performance prediction is presented. This method is based on analytical equation (15) which can be applied for regenerators operating in broad range of period time length. The accuracy of the method has been compared for slim regenerators with the robust method by Hill and Willmott [A. Hill, A.J. Willmott, A robust method for regenerative heat exchanger calculations, Int. J. Heat Mass Transfer 30 (1987) 241] and for corpulent regenerators with the solution by Hill and WillMott [A. Hill, A.J. Willmott, Accurate and rapid thermal regenerator calculations, Int. J. Heat Mass Transfer 32 (1989) 465]. (c) 2006 Elsevier Ltd. All rights reserved.