Cryogenic fluids, such as liquid oxygen (LOX) and liquid hydrogen are used as the propellants of space vehicles. Before initiating the normal operation state, all elements in the cryogenic system need to be chilled down by consumption of the incoming the cryogenic liquid. As a result, the heat transfer characteristics during the chill-down process are extremely concerned by engineers. This paper describes the experimental research on the line chill-down process with LOX. The experiments are conducted under various mass flux conditions on a stainless steel horizontal pipe with the dimensions of 12.7 mm outer diameter, 1.25 mm wall thickness, and 7 m length. The heat transfer characteristics in various heat transfer regimes are experimentally examined and analysed for comparison with those in chill-down processes with liquid nitrogen. Additionally, the accuracy of the previously suggested transient heat transfer correlations is evaluated being based upon the current experimental data.