Monosodium citrate is a monobasic salt of citric acid and is produced by partial neutralisation of citric acid with a high purity sodium source and subsequent crystallisation. It is supplied as anhydrous material. As partially neutralised salt it occupies an intermediate position between citric acid and the neutral or weakly alkaline trisodium citrate. Monosodium citrate is used if a buffering effect is required or if citric acid is considered to be too aggressive for the formulation. Monosodium citrate is also less hygroscopic than citric acid, thus less prone to caking and preferred in critical formulations such as dry blends, instant preparations or tablets.

Monosodium citrate is a white, odourless, fine or crystalline granular powder with slightly acidic taste. It is easily soluble in water and practically insoluble in ethanol.

It is used whenever a buffering effect compared to the pure acid is required (e.g. acid sensitive ingredients are present).

For preparations which are sensitive to water (e.g. sodium bicarbonate in effervescent tablets) the anhydrous monosodium citrate can replace water containing ingredients. Due to its high decomposition temperature (>200°C) and low water content (<0.4 %), it is also the preferred acid source in baking powder or blowing agents in order to prevent premature reaction between acid and alkaline source.
When used as endothermic blowing agent in the plastics industry, it is the preferred food grade, non-toxic alternative to exothermic blowing agents such as azo compounds (e.g. azodicarbonamide), hydrazine derivatives or semicarbazides. Monosodium citrate D is specifically used in this application due to its approx. 10°C lower decomposition temperature compared to monosodium citrate F3500 and is also recommended for other applications where a quicker dissociation is required.