Wall-liquid mass transfer for Taylor bubbles rising through liquid column in vertical tubes is an important and fundamental topic in industrial processes. In this work, the characteristics of wall-liquid mass transfer for this special case of slug flow were studied experimentally by limiting diffusion current technique (LDCT). Based on the experimental results and the analysis of hydrodynamic mechanisms, it was proposed that four different zones exist, i.e. the laminar falling film zone, the turbulent falling film zone, the wake region and the remaining liquid slug zone. The corresponding correlations for all these zones were developed.