* Hydrochloric acid (HCl), which is a strong acid.

* Potassium hydroxide (KOH), which is a strong base.

Here's the reaction:

HCl (aq) + KOH (aq) → KCl (aq) + H₂O (l)

This is a neutralization reaction where the acid and base react to form salt (KCl) and water (H₂O).