Protium or hydrogen-1 is the most common isotope of the element hydrogen, with one proton, one electron, and no neutrons.

Protium may also refer to:

• Protium (plant), a genus of chiefly tropical American trees in the family Burseraceae, having fragrant wood
• Cadence Protium, hardware accelerated prototyping platforms for early software development by Cadence Design Systems

• Protonix, a commercial name for pantoprazole, a proton pump inhibitor drug
• Protonium, an onium, a proton-antiproton pair
• All pages with titles beginning with Protium
• All pages with titles containing Protium