There is substantial research focused on pharmaceutical cocrystals and salts because of their capacity to modify the physicochemical characteristics of active pharmaceutical ingredients . Here, we aimed to explore crystal engineering strategies to increase solubility and cost-effectively improve palatability. As a basic drug, TBZ is more soluble in acidic solutions due to the increase in charge resulting from the protonation of benzimidazole . We reasoned that an acidic salt could provide the proton for increased solubility while bringing additional desirable qualities, like sweetness or better taste. Such salts can feature various other improvements in the physicochemical properties . Given that saccharin (HSAC) and its sodium salt is already used as an excipient in tablets and suspensions and is commonly used in cocrystal former , we sought to investigate the possibility of using this molecule for a dual purpose-to improve the solubility of TBZ and to provide a sweeter formulation. Saccharin is a weak acid with a relatively low pKa of 1.6, facilitating proton transfer to the TBZ molecule with a pKa of 4.7. Additionally, we selected three acids that are commonly used as food and medicine additives (Scheme 1): fumaric acid (H2FU), maleic acid (H2MA), and oxalic acid (H2OX). The pKa difference between benzimidazolium and the salt formers ranges between 1.67 and 3.47 (Table ), allowing for a readily occurring proton transfer in solution and solid state . This results in a salt formulation of TBZ. We prepared five salts with a broad range of aqueous solubility and dissolution rates. Three salts were structurally characterized using single crystal X-ray diffraction (SC-XRD) and one using powder X-ray diffraction (PXRD). The phase purity of the salts was confirmed by PXRD, infrared (IR) spectroscopy, thermogravimetric analyses (TGA), and differential scanning calorimetry (DSC). Due to the need to produce anthelminthic drugs in large quantities with minimal costs, we used a mechanochemical method. Solid-state synthesis provides a solventless, easily scalable route using simple, readily available ball-milling equipment . We report a broad tunability of the aqueous solubility of thiabendazole by salt formation. Reformulation with maleic acid provided a 60fold increase in solubility, while saccharin and oxalic acid gave a modest improvement. Fumaric acid resulted in a solid with only slightly higher solubility. The crystallographic studies enabled detailed structure-properties correlations, particularly focused on the templating abilities of the acid onto TBZ packing . Furthermore, we explored the possibility of forming phase mixtures of TBZ and two co-formers. The study's conclusions can inform new strategies for designing and manufacturing improved formulations of TBZ and related anthelmintics.