Prof Ong is extensively involved in national and international research related to pre-hospitals emergency care, health services research, and medical devices. His research addressed issues such as out-of-hospital cardiac arrest (OHCA), improving ambulance deployment, acute myocardial infarction care and emergency care, etc. He has patented inventions using Heart Rate Variability for risk prediction of acutely ill patients and cooling solutions for therapeutic hypothermia. Prof Ong has been awarded multiple national research grants and has accumulated over $27 million in research grants for his studies which include geospatial diseases mapping, clinical drug trials, resuscitation and cardiovascular sciences, pre-hospital emergency care, and biomedical engineering. He has published close to 200 papers in both local and international journals.