Control of aggregation and gelation of colloidal particles are among important issues in processing of disperse systems. We present an experimentally validated approach to kinetic modelling based on master curves for aggregation and gelation. The master curves depend on basic physicochemical properties of primary particles, which are reflected in terms of the cluster fractal dimension and kernel kinetic exponent. We also analyse interplay between aggregation and diffusion at small length scales in the process of formation of gel domains in imperfectly mixed colloidal dispersions.