This research studied the preparation of chitosan/hydroxyapatite composite via membrane diffusion process. In this process, membrane was used to slow down the diffusion rate of Ca²⁺ions and PO₄³⁻ions to chitosan solution, resulting in hydroxyapatite formation into chitosan solution. The obtained mixture solution was then cast to be film. To study the appropriate condition to prepare the chitosan/hydroxyapatite composites, diffusion time 72 hour and chitosan concentration 1.75 wt% were found to be the appropriate condition for membrane diffusion process. SEM observation showed cluster of needle-shaped of hydroxyapatite when using 0.2 M calcium chloride solution and 0.12 M disodium hydrogen phosphate solution, but showed the aggregation of hydroxyapatite when using higher concentration of both solutions. From ATR-FTIR showed specific peak of phosphate group. XRD showed 2Ө peak of hydroxyapatite crystal. From these results indicated that hydroxyapatite can be synthesized into chitosan solution with good dispersion by membrane diffusion process. Due to some Ca²⁺ions remaining inside chitosan molecule after hydroxyapatite formation when increasing Ca²⁺ions and PO₄³⁻ions concentration, resulting in the chelate formation between chitosan and the remaining Ca²⁺ions.
