A critical heat flux (CHF) study of the vertical up-flow of water through multiple thin rectangular channels was conducted. Pressures varied from 89.8 to 115 kPa, inlet temperatures from 291 to 306 K, and mass fluxes from 9.5 to 39 kg m(-2) s(-1). Electrical resistance heaters embedded in aluminum provided a uniform heat flux. A more universal and robust CHF correlation based on the geometry of the Advanced Test Reactor at Idaho National Laboratory was developed. This new CHF correlation predicts 126 data points from this and three previous studies within an error of +/- 8.5% with a 95% confidence. (C) 2007 Elsevier Ltd. All rights reserved.