Is it possible to sell an invention without patenting it?

File a provisional yourself, the filing fees for a micro-entity are very cheap around $100. That will give you a year to go sell it to someone.

First, a patent is not a necessary condition for selling an invention or solution.

You can also protect it by contract.

If a potential buyer likes your patent, he may buy it and patent it himself.

Second, there are two concepts. One is a patent and the other is a patent application.

If you file a patent application, you occupy the filing date. You do not have to have a patent or get a patent, but you have the possibility to get a patent. Then, anybody who would like to use your idea shall think about it and negotiate with you.

If you do not file a patent application, there is a risk that your invention goes to the public when you tell potential buyers about your patent.

I would like to clarify one point in addition to Yang Guoquan response, being specified that this applies regardless of the law to be applied..

An invention assumed patentable but not yet actually patented, constitutes what is called "a patentable knowledge." This is, no more, no less, an element of know-how.

This patentable knowledge can be transferred by contract, communicated as standard features which element of expertise. You can sell a patentable invention as you can sell a (utility) patent or communicate know-how.

But there are several small differences between the sale of the invention itself and the actual assignment of the patent on the invention: when you sell a supposed patentable invention you must:

- define the invention and its technical specifications in contractual technical appendices,
- give the right to patent such invention, that is to say the "right to a patent,"
- and renounce to patent the said invention (except to keep the right to make use of the invention if your assignee agrees).

In addition, a not yet patented invention has value only if it is secret and, as assignor, you must ensure, in the assignment contract, a total confidentiality on the characteristics of the invention as on the agreement in itself.

I hope I was enough clear.
Feel free to revert to me for all details.

Sincerely yours,
Simon