To reduce the total time used in the lyophilization process and to develop appropriate formulation of Green Pit Viper antivenin product. The effect of freezing steps on the secondary structure of F(ab’)2 Green Pit Viper antivenin are evaluated. Optimized freezing step is found to have an average cooling rate of 1.86°C/min until -40°C is reached and annealed for 30 minutes (Rapid3). Lyophilized products obtain by Rapid3 freezing step are analyzed for their physical appearances, F(ab’)2 secondary structures, moisture contents, crystallinity and stability after 3 months. Primary and secondary drying are studied and adjusted. Lyophilized products obtained are again analyzed similarly to the previous section. The optimal lyophilization process is Rapid3 freezing step, primary drying is done at -25°C for 6 hours and 0°C for 12 hours (pressure 300 mTorr). Heating time from 0°C to 30°C is 1 hour and final secondary drying at 30°C continues for another 2 hours under pressure of 100 mTorr. The total lyophilization time is approximately 24 hours. Green Pit Viper antivenin is formulated with proper stabilizing agent and freeze dried with optimal lyophilization process. The best formulation is 0.7 mg/ml F(ab’)2 Green Pit Viper antivenin and 2% w/v glycine which 4 ml of the formula is filled into 6 ml vial. Potency test is done using “Mouse Neutralizing Test” which resulted in a potency of 0.966 mg/ml. The developed formula has the potency within the required specification of Queen Saovabha Memorial Institute for Green Pit Viper antivenin products (> 0.7 mg/ml), good physical appearance, retain its initial secondary structure and shows satisfying 3 months stability results.