Acyclovir conventional tablets have been used for long period for the treatment of viral infections. When orally administered, it is showing slow and incomplete absorption from gastrointestinal tract. The total oral bioavailability of acyclovir is between 15–30% due to poorly soluble drug and short plasma half life (3 Hrs). Oral bioavailability of acyclovir can be achieved by improving the solubility and dissolution rate. Several techniques have been used to improve the solubility and dissolution rate of acyclovir such as solid dispersions and spherical agglomerates and complexes. Co- crystals recently been used for improving oral solubility and dissolution rate of the drugs. The present investigation of the work is to prepare acyclovir co-crystals with chitosan by using solvent change method to improve the solubility and dissolution rate of acyclovir. The second objective of this work is to extent the maximum bioavailability of acyclovir by retaining the drug in gastric region for longer time. To achieve this goal, the prepared co-crystal is made to float in the gastric region by using sodium alginate as non-effervescent floating technique.