addition of a proton to an atom, molecule, or ion, forming the conjugate acid

Protonation is the addition of a hydrogen ion to a substance. A hydrogen atom normally contains 1 proton and 1 electron. When the hydrogen atom is oxidized, it loses its electron, leaving a H+. The H+ is the same as a proton. Substances are protonated when hydrogen ions are added to them. For example, when ammonia (NH3) is protonated, it forms ammonium ions, NH4+. A substance is protonated by a substance more acidic than it. The acidic substance is deprotonated.