The discovery of gunpowder dates back to at least 1000 years ago, which is why it is hard to find out exactly when and how it happened.

There are also several differing stories and myths around its discovery in different areas of the world. It seems to be agreed nowadays though that the initial discovery was in China, and from there it spread rather than being independently invented elsewhere.

To speculate how it might have been invented, it's helpful to consider the three ingredients of "classic" gunpowder. Two (sulfur and charcoal) are fuels, and the third (potassium nitrate, or saltpeter) is an oxidant, meaning it provides oxygen for the combustion of the fuels. To my mind, discovering that certain compounds can act as oxidizers, accelerating the burning of some fuels more than just air, is the key step towards gunpowder. Once you know or suspect that, you can start optimizing by playing with different fuels, fuel combinations, and ratios of all the components. In that context it is interesting that saltpeter had been known in China since around 2000 years ago, and some people think that mixtures of saltpeter and sulfur were used as medicines. Eventually, the flammability of such mixtures and related ones was discovered, quite possibly (as with so many great discoveries) by accident. From there, further experimentation probably began. At that time, there was no understanding of chemistry as we have it today, but alchemists were experimenting and writing down their accounts (which is how we can trace these discoveries today)

It appears that more than a hundred years passed between the initial discovery of flammable saltpeter mixtures and their use in weapons.

The earliest written record of the formula is from China in 1044, but the Chinese had been using the stuff for at least 150 years before then. I'm not sure whether the first gunpowder devices were weapons or fireworks.

The exact details of discovery of gun powder is probably still under some debates (Refer to wiki). However, there are some documents showing the descriptions and applications of gun powder since ancient 9th century China. It has something to do with the alchemists and the emperors. In the old days, it was the ultimate dream for the emperors to live forever so that they could rule forever. Another factor was probably the desire for gold or money to rule the country. Therefore, the seeking of immortality and gold promoted the activities like making pills using furnaces or other methods of production. The discovery of gun powder was probably an accidental event.

Thank you for your question! Gunpowder has a long history that begins more than a THOUSAND years ago in China! The first record of gunpowder formula appears in Chinese texts from the Song dynasty, while gunpowder had probably been used for at least 100 years before that for fire arrows. From China, gunpowder spread throughout Asia and Europe, while the earliest western account is from a British philosopher in the 13th century (a few hundred years after the first Chinese records). However, some of the ingredients for gunpowder, like saltpeter, were known to the Chinese 1000 years prior to gunpowder records (so 2000 years ago). You can learn more about gunpowder here:

gunpowder