The design of bubble column for industrial applications is well known under near ambient pressure and temperature conditions, contrary to high pressure and temperature conditions. Accurate data on the evolution and behaviour of the bubbles is proposed as a basis for the evaluation of the surface area developed in the column and further design of such reactor. Two columns are used for the experiments: a small column (8 mL) with a total visualisation of the flow, and a bigger one (1 L), necessary for the scale up. Main results show that the influence of pressure and temperature are significant on the behaviour of bubbles and bubble size distribution and must be characterized and considered for the design of the columns in such conditions. The results allow the determination of two correlations: one for the bubble diameter and the other one for the bubble rise velocity, considering different parameters, and especially the superficial gas velocity in saturated conditions. These correlations are a basis to determine mass transfer correlations for the design of bubble column at high pressure and temperature conditions. (c) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.