A pharmaceutical cocrystal is a multicomponent crystalline entity where at least one constituent is an API. Components interact with non-ionic and non-covalent forces [1]. Cocrystals have been widely adopted in the pharmaceutical industry because of their inherent stability (relative to the crystalline state) and the possibility of increased solubility and dissolution rate in respect to single components. An initial screening revealed that by melting then cooling the molar ratio 1:1.5 of phenacetin and benzamide a single melting point (Mp) at 98.260°C was observed. This is significantly different from the Mp of the single components. The hypothesis was that the process generated a cocrystal. Hence, eleven physical mixtures of phenacetin and benzamide with different molar ratios were prepared to identify the most feasible molar ratio to generate the cocrystal. In DSC, the physical mixtures were heated above the melting point and then cooled at 5°C/min with multiple heating cycles being conducted. Preparation was also attempted by rapid solvent evaporation from mixtures solubilised in ethanol (by rotary evaporation) as an alternative method to generate phenacetinbenzamide cocrystals. Among those tested, three molar ratios showed a single Mp at 98.43±1.06°C for both preparation methods, those molar ratios of phenacetin:benzamide were, 1.5:2, 1:1.5 and 0.5:1 (Fig. 1). XRD was used to evaluate variation in the crystallography of the generated products and significant differences were revealed between those identified as containing cocrystals and the pure compounds (Fig. 2). Fig. 1. DSC overlay screening Fig. 2. Difractogram overlay of products and physical mixtures The three selected physical mixtures will be further evaluated to identify the best conditions for the generation of pure phenacetin:benzamide cocrystals. The three selected molar ratios will be further analysed to identify a phenacetin:benzamide ratio that forms a cocrystal without impurities. The physicochemical properties of the generated cocrystal will be studied and characterised.