We directly visualised the dynamical mass-transfer process from a zigzagging rising CO2 bubble (2.9 mm in equivalent diameter) to its surrounding liquid by using laser-induced fluorescence/8-hydroxypyrene-1, 3, 6-trisulfonic acid (LIF/HPTS). We measured the surrounding liquid motion induced by bubble buoyancy using particle image velocimetry (PIV). Further, the CO2 concentration profile inside the bubble wake was measured directly by using a newly developed photoelectric optical fibre probe (POFP). Making the best and mutually complementary use of these three measurement techniques, we discuss the relationship between the mass-transfer process and the flow structure. We succeeded in clearly visualising CO2-rich regions corresponding with the dynamical mass-transfer process from the bubble to the wake and the surrounding liquid (LIF/HPTS). We also obtained a CO2 concentration profile in the bubble wake (the POFP). It was found that the CO2-rich regions were formed into horseshoe-like vortices; the CO2 concentration at the centre region of the wake was the highest, and the concentration decreased toward the outer edge of the wake; the CO2-rich regions were transported widely into the surrounding liquid by the advective liquid-phase flows (PIV). In addition, we discuss the performance and characteristics of the newly developed POFP.