Alkili Salt might do the trick.
Several acid spells, though I can't remember which right now, mention a gallon of water is enough to wash it away.
In a roleplaying game my best bet would be some lye. Or, as Reaver said, alkali salt.
But I would never suggest to try that irl.
And if you try water then only if you have large quantities at your disposal. Small amouts of water just mage the acid get hot and burn you in addition to being corrosive.
Lye would likely cause as much damage as the acid.
A basic salt, like calcium carbonate, could neutralize the acid without being strong enough to cause chemical burns itself.
