The dissolution rate of single carbon dioxide (CO,) bubbles in a strong alkaline solution was investigated experimentally and numerically. We developed a system that uses a charged-coupled device (CCD) camera coupled with a microscope to track the rising bubble and we photographed the rising CO, bubbles in 0.01-1 M sodium hydroxide (NaOH) solutions. From these photographs we measured the bubble size and the rising speed, and from this data we estimated the drag coefficient, C-D, and the Sherwood number, Sh, for CO, bubbles dissolving in NaOH solutions with simultaneous chemical reactions. Assuming chemical equilibrium at the bubble gas-liquid interface, we also estimated the dissolution rate of bubbles in alkaline solutions using numerically estimated dissolution rates in water. Comparing the numerical and experimental results indicates that chemical equilibrium is not achieved at the bubble surface because the values of the calculated Sh were larger than the measured Sh. Next, we numerically estimated C-D and Sh corresponding to the "stagnant cap model" by directly solving the Navier-Stokes and the convection-diffusion equations for a CO, bubble dissolving in a strong alkaline solution with simultaneous chemical reactions. We assumed that chemical reactions near the bubble were nonequilibrium. We included the species source-sink terms for the chemical reactions in the convection-diffusion equation. We compared these results with the measured rising speed and dissolution rate. This comparison shows that the experimental and numerical results are in good agreement and that the dissolution rate with chemical reactions can be estimated within about 10% of measured values, even for nonequilibrium chemical reactions near the bubble.