Basic catalysis! The basic properties of hydrotalcites (see picture) make them attractive for numerous catalytic applications. Probing the basicity of the catalysts is crucial to understand the base-catalysed processes and to optimise the catalyst preparation. Various parameters can be employed to tune the basic properties of hydrotalcite-based catalysts towards the basicity demanded by each target chemical reaction.Hydrotalcites offer unique basic properties that make them very attractive for catalytic applications. It is of primary interest to make use of accurate tools for probing the basicity of hydrotalcite-based catalysts for the purpose of 1) fundamental understanding of base-catalysed processes with hydrotalcites and 2) optimisation of the catalytic performance achieved in reactions of industrial interest. Techniques based on probe molecules, titration techniques and test reactions along with physicochemical characterisation are overviewed in the first part of this review. The aim is to provide the tools for understanding how series of parameters involved in the preparation of hydrotalcite-based catalytic materials can be employed to control and adapt the basic properties of the catalyst towards the basicity demanded by each target chemical reaction. An overview of recent and significant achievements in that perspective is presented in the second part of the paper.