Concentration gradients due to mass transfer at rising droplets can lead to a variation of the interfacial tension and induce Marangoni convection. As a result, mass transfer is intensified and the rise behaviour of the droplet is affected. To investigate these phenomena numerically, a CFD-code was developed and implemented in the CFD-toolbox OpenFOAM (R). The code takes the coupling of momentum and mass transfer as well as interface deformation into account. Here, results of full 3D simulations are presented and validated.