Chlorthalidone nanocrystals were developed via lyophilization with the aid of cryoprotectants.To produce stable and free-flowing chlorthalidone nanocrystals, various cryoprotectants including trehalose, mannitol, sucrose, polyethylene glycol (PEG), glycerol, and glucose were considered, and their impact on the viability and characteristics of the nanocrystals were investigated.This was accomplished by characterizing the nanocrystals by considering different parameters such as particle size, polydispersity index (PDI), surface charge, surface properties, encapsulation efficiency, loading capacity, prolonged stability studies, and subsequent release kinetics.The outcomes of this research revealed that formulation (FC7) containing mannitol as a cryoprotectant in 7.5% concentration during lyophilization (freeze drying) produced an optimized nanocrystal formulation without any change in the structure and characteristics.However, nanocrystals obtained via trehalose, PEG, and sucrose showed some extent of aggregation or agglomeration among the crystals.The particle size and surface charge of the optimized nanocrystals were 118 nm and -28.2 mV, resp.The in-vitro drug release of chlorthalidone nanocrystals was increased up to 4-fold, approx. (91.6% in 90 min) when compared with pure chlorthalidone drug (23.37% in 90 min) because of the decrease in particle size, thus may significantly enhance the bioavailability of the drug.The surface morphol. of the obtained nanocrystals was determined by SEM, which revealed better consistency of nanocrystals with multispectral results.Moreover, stability studies indicated that the crafted nanocrystals were stable at normal room temperature (25 °C) for 6 mo.From the obtained results, it was concluded that the mannitol-like cryoprotectant could be effectively used in the lyophilization process to produce stable and free-flowing nanocrystals loaded with chlorthalidone-like BCS class IV drug moieties.