Hydrochloric acid is HCl. This is an ionic substance so in water it breaks apart into ions H++Cl−
Potassium Hydroxide is also an ionic substance it also breaks apart in water into ions K++OH−
So the complete ionic equation for the reaction is
H++Cl−+K++OH−=K++Cl−+H2O
The Hydrogen ion and the Hydroxide ions combine to form water.
The net ionic equation is
H++OH−=H2O
This is because the Cl−+K+ ions do not undergo any changes therefore are not part of the net ionic equation.