| H3O+ + e− → Hads + H2O | (Volmer adsorption) |
| Hads + H3O+ + e− → H2 + H2O | (Heyrovsky desorption) |
| Hads + Hads → H2 | (Tafel desorption) |
| H3O+ + e− → Hads + H2O | (Volmer adsorption) |
| Hads + H3O+ + e− → H2 + H2O | (Heyrovsky desorption) |
| Hads + Hads → H2 | (Tafel desorption) |