Objective: To study the safety and pharmacokinetic (PK) profile of S-oxiracetam (S-ORT) in healthy volunteers, so as to provide a safe and reasonable basis for the application of formulation in phase II clinical programs. Methods: In part 1, subjects were intravenously administered single-ascending dose (2.0-8.0g) S-ORT. In part 2, subjects were treated by two-sequence, two-period crossover design. In part 3, subjects were intravenously injected with 4.0 g S-ORT once a day for 7 days. The biological samples were collected to evaluate the PK parameters and urine excretion rate. The safety profile of the drug was also evaluated throughout the test process. Results: Only 1 subject displayed a mild AE (adverse event) without obvious dosage-related AE, and SAE (serious adverse event). Within the range of 2.0-8.0 g for a single dose, Cmax, AUC0-t, and AUC0-∞ increased with an increase of dosage. The urine excretion rate of the prototype drug was approximately 60%. The consecutive administration of drug could not cause a substantial accumulation of S-ORT. The plasma drug concentration-time curves for both S-ORT and R-oxiracetam (R-ORT) were found to be almost identical. Conclusions: The safety, tolerance and PK characteristics of S-ORT in the healthy volunteers within a range of 2.0-8.0 g for a single dose, or with 4.0 g for 7 consecutive days were found to be acceptable. The pharmacokinetics of S-ORT and racemic oxiracetam (ORT) were observed to be basically the same. The injection of S-ORT can be used at once-a-day dosing regimen for Phase II clinical studies.