This is the first of a two-part series which presents the experimental results of the chilldown of a thin walled stainless steel tube with liquid nitrogen under a wide range of pressures and mass fluxes in terrestrial gravity. Data is presented in this paper for a vertically upward (against gravity) flow orientation. The experimental data covers mass fluxes ranging from 6 to 1650 kg/m(2) s (liquid Reynolds numbers ranging from 850 to 231,000), equilibrium two-phase flow qualities from -0.13 to 0.4, inlet subcooling from 0 to 10 K and local pressures from 150 to 720 kPa. The temperature and pressure measurements were made at two axial distances of 14.9 cm and 40.1 cm from the inlet. Analysis is presented on the effects of the mass flux, equilibrium quality, inlet subcooling, pressure, and axial distance from the tube inlet on the measured film, transition, and nucleate boiling heat transfer coefficients as well as the critical heat flux. (C) 2016 Elsevier Ltd. All rights reserved.