Jan Ingenhousz: The Man Who Discovered Photosynthesis

If you were paying attention in high school science class, you would know that photosynthesis is a hugely important part of the natural world. It’s the means by which plants take light energy and chemical energy, and turn it into fuel for other organisms. In simple terms, they take sunlight, and use it to turn carbon dioxide into glucose, creating oxygen as a byproduct of this.

So basically, plants are hugely important on the planet because they essentially help keep us alive. Almost makes you rethink being a vegetarian, right? Anyway, what you may not know is that Jan Ingenhousz is the guy who discovered photosynthesis, and changed the way we understand our planet as a result. It would have been Jan’s 287th birthday this month, so let’s go back in time, and find out a little more about him.

Early life

Ingenhousz was originally born in the Dutch Republic, and decided to start studying medicine from the age of around 16. He had a keen interest in electricity, but eventually opened a medical practice. In 1764 he began to travel Europe working with smallpox and learning about inoculation practices. In 1768 he traveled to Austria, where he successfully inoculated the royal family against smallpox, becoming the court physician, and settling in Vienna.

Work with photosynthesis

As we know, Ingenhousz wasn’t just an accomplished scientist in the field of inoculation – he also developed a keen interest in photosynthesis. This was triggered by a meeting he had with British chemist Joseph Priestley. After moving to Great Britain, hew met Priestley at his home in West Yorkshire. Priestley’s work proved to be highly influential to Ingehousz, and he took what the Englishman had done, and expanded on it to discover how plants create oxygen.

Breakthrough moment

In 1778, Ingenhousz built on the work first started by Priestley. The British chemist had started some of the first works to try to understand different types of air, i.e., oxygen and carbon dioxide, etc. It was this work that formed the basis for Jan’s work, and his breakthrough moment came when he discovered how the influence of sunlight on a plant could cause it to produce oxygen. This was a huge breakthrough, and his tests with mice proved to be highly successful in helping us understand more about this.


The most important thing Ingenhousz found out was the discovery that light is the most important part of the process. Without his work, and the works of Priestley before him, we would not understand the importance of plants, and sunlight, and how they help us to live and breathe. This is one of the most important legacies in science, and has altered the way we study plants and nature.

Jan Ingenhousz is probably a name you aren’t familiar with, but now you’ll be happier knowing who he is. This guy is somebody who should be revered, and known all across the world for his discovery. We take so much of science for granted, and there are not many scientific discoveries that are as important as this one.