Many industrial processes deal with gas bubbles, e.g., the chlor-alkali processes or a side reaction in metal deposition reactions. It is therefore very important to describe the influence of gas bubbles on the fluid flow in a quantitative way. In the present paper, the two-phase flow is both experimentally characterized and numerically modeled in a reactor with a rotating flow field such as the inverted rotating disk electrode (IRDE). Polarization curves of the hydrogen evolution in 0.1 M Na2SO4 at pH 2.5 are recorded at different rotation speeds. The bubble dispersion and size distribution of the hydrogen bubbles are determined by laser marked shadowgraphy and interferometric laser imaging for droplet sizing. Concerning the numerical investigations, in the first step the single-phase flow solution in the vicinity of the IRDE is compared to the analytical solution of the flow field, as proposed by Cochran [Proc. Cambridge Philos. Soc., 30, 365 (1934)]. In the following step, an Eulerian-Lagrangian two-phase flow model is used to track the bubbles. Two-way momentum coupling effects between bubbles and electrolyte flow are taken into account. The calculated two-phase flow field compares well against the experimental data of the two-phase flow field obtained from the optical imaging techniques.