Introduction: We conducted basic hands-on training in oxygen therapy and ventilatory management of coronavirus disease-2019 (COVID-19) patients to health care workers (HCWs) at our tertiary care hospital. We designed this study aiming to find out the impact of hands-on training in oxygen therapy for COVID-19 patients on the knowledge and degree of retention of this gained knowledge 6 weeks after the training session among HCWs. Materials and methods: The study was conducted after obtaining approval from the Institutional Ethics Committee. A structured questionnaire consisting of 15 multiple-choice questions was given to the individual HCW. This was followed by a structured 1-hour training session on “Oxygen therapy in COVID-19”, following which the same questionnaire was given to the HCWs with the questions in a different order. After 6 weeks, the same questionnaire with questions in a different format was sent to the participants as a Google form. Results: A total of 256 responses were obtained for the pre-training test and post-training test. The median [IQR] pre-training test scores and post-training test scores were 8 [7–10] and 12 [10–13], respectively. The median retention score was 11 [9–12]. The retention scores were significantly higher than the pre-test scores. Conclusion: About 89% of the HCWs had a significant gain of knowledge. About 76% of the HCWs were able to retain knowledge, which also means the training program was successful. A definitive improvement in baseline knowledge was observed after 6 weeks of training. We propose conducting reinforcement training after 6 weeks of primary training to further augment retention.