A solid-liquid flow in stirred tanks occurs frequently in different branches of process engineering where particles need to be suspended in a liquid. Computational Fluid Dynamics (CFD) simulations of this type of flow on industrial scales are feasible if the closure models implemented therein are appropriate. A large number of closure models exist but, due to a lack of data sources for validation, no systematic assessment of these different models has appeared so far. The present dataset aims to accumulate a comprehensive ''CFD-grade'' database based on experiments on single-phase and two-phase flows in a standardized stirred tank with a diameter of 90 mm. The velocity fields of the liquid phase (deionized water) and, in the two-phase case, the solid phase were measured with Particle Image Velocimetry (PIV) and Particle Shadow Velocimetry (PSV), respectively. The experiments cover a range of parameters to achieve an extensive database. A narrow particle distribution of nearly neutrally buoyant particles (polyethylene spheres), as well as heavy particles (glass spheres) in suspension, are considered over a range of particle diameters (63µm-500µm), solid volume fractions (0.025 vol% - 0.1vol%), as well as impeller rotation speeds (650rpm - 1500rpm). The transient flow field on the plane midway between two baffles was recorded over 50 impeller rotations to achieve statistical significance. The time-averaged (or angle-resolved) mean and fluctuation velocities were then obtained by averaging the transient data in the laboratory frame of reference (or the frame of reference rotating with the impeller). The data is organized and analyzed as described in the corresponding journal publication "Solid-liquid Flow in Stirred Tanks: ”CFD-grade” Experimental Investigation".