Gas-liquid mass transfer in non-Newtonian fluid systems is important in many chemical and biochemical processes. Having a good understanding of gas-liquid mass transfer contributes to achieving the optimization of design and the energy-efficient operation. The mass transfer performance in tap water and carboxyl methyl cellulose (CMC) aqueous solutions with different weight percentages (0.3 wt%, 0.4 wt%, 0.5 wt% and 0.6 wt%) were investigated experimentally. The CMC aqueous solution was shear-thinning non-Newtonian fluid. In this study the apparent viscosity of the solutions ranged from 0.01 to 0.1 Pa s. As expected, the liquid phase rheology had a great effect on the gas-liquid mass transfer performance. The volumetric mass transfer coefficients in CMC aqueous solutions were much smaller than those in tap water, and the value decreased from 3.04 x 10(-3) s(-1) to 2.8 x 10(-4) s(-1) with the increase of the weight percentage of CMC aqueous solutions. The mobility of the gas-liquid interface in tap water and CMC aqueous solutions was identified by the dimensionless diameter number. It was found that the mobile gas-liquid interface prevailed in tap water, while bubbles behaved as rigid particles in relatively high weight percentage of CMC aqueous solutions (0.5 wt% and 0.6 wt%). The liquid film mass transfer coefficient could be approximated by theories for mobile and immobile gas-liquid interfaces in tap water and CMC aqueous solutions, respectively. Based on the liquid phase rheology and the mobility of the gas-liquid interface, the dimensionless correlations were proposed to describe the mass transfer process in Newtonian and non-Newtonian fluids. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.