In this study, we are particularly interested in the interaction mechanism of hydroxy-carboxylic acids such as citric and tartaric acid. Numerous studies have examined the effects of citric acid and, in some cases, tartaric acid on the hydration of Portland cement . The observed retarding effect was explained by the formation of a protective layer around the cement grains through the adsorption of the additives onto the surface of the particles . This is supported by other studies reporting that set retarders slow down or inhibit the dissolution of the cement grains . Adsorption studies revealed that the fruit acids predominantly affect the C 3 A dissolution, which is the main reacting clinker phase in the first minutes after water addition . However, this was observed in systems where dissolution was not completely separated from nucleation of hydrate phases. This means that the retarding effect of citric and tartaric acid on the initial dissolution rate of cement clinker phases can also be influenced by nucleation events. Rottstege et al. used 29 Si solid-state NMR of fresh cement paste to investigate the influence of citric and tartaric acid. They found a modification to the hydration process caused by complete inhibition of the silicate condensation to Q 1 and Q 2 species within the C-S-H phases and an enhanced formation of ettringite . However, further knowledge regarding the effect of these additives on the crystallization mechanisms of cementitious hydrate phases, including C-S-H, CH, and ettringite, remains relatively limited . A suitable protocol to study the nucleation and growth of crystalline phases, pioneered by the Cölfen group, is based on potentiometric titration . The principle of this setup is based on titrating an aqueous solution of a salt containing one ion (e.g., carbonate, Na 2 CO 3 ), with a solution containing the second ion (e.g., calcium, CaCl 2 ) to create a supersaturated, homogenous solution of the phase of interest (CaCO 3 in this example). Based on this titrimetric method, several crystallization studies of a range of minerals, including Ca(OH) 2 and C-S-H, were designed to improve the understanding of the crystallization mechanism and enlighten the influence of additives in this process . These studies revealed that a non-classical crystallization pathway (i.e., the formation of amorphous prenucleation clusters that condense to crystal nuclei instead of classical monomer by monomer growth) is often the rule rather than the exception and that additives significantly influence the nucleation and growth processes. This study focuses on three compounds with similar structures -citric acid, tartaric acid, and succinic acid. We chose to include succinic acid because it is structurally related to tartaric acid: it has the same dicarboxylic motif. Still, it lacks the hydroxyl groups, which is interesting because it allows us to examine the structure-effect connection of the hydroxyl groups. We decouple the dissolution and nucleation processes of cement hydration and investigate the influence of functional molecules on each step separately. Through these experiments, we strive to advance the understanding of how functional molecules influence cement hydration.