Touch attacks come in two types: melee touch attacks (for touches made with, say, your hand) and ranged touch attacks (for touches made with magic rays, for example).
and this:
Holding the Charge:If you don’t discharge the spell in the round when you cast the spell, you can hold the discharge of the spell (hold the charge) indefinitely. You can continue to make touch attacks round after round.
Alternatively, you may make a normal unarmed attack (or an attack with a natural weapon) while holding a charge. In this case, you aren’t considered armed and you provoke attacks of opportunity as normal for the attack. (If your unarmed attack or natural weapon attack doesn’t provoke attacks of opportunity, neither does this attack.) If the attack hits, you deal normal damage for your unarmed attack or natural weapon and the spell discharges. If the attack misses, you are still holding the charge.
Missing with a touch range shocking grasp would leave the caster with a held charge.If you don't want to get into the Touch/Ranged Touch discussion, please answer the question when considering Shocking Grasp instead.