He conducted experiments in the late 1700s, where he observed that plants release bubbles of gas when exposed to sunlight. He further determined that this gas was oxygen by showing it could support combustion.

While other scientists had previously made observations related to plant respiration and photosynthesis, Ingenhousz was the first to definitively prove that plants produce oxygen. His findings were crucial in understanding the process of photosynthesis and its role in supporting life on Earth.