Can you cast Krosan Grip in response to the activated ability of an artifact?

Krosan Grip has Split Second (CR 702.61a), which means that while it is on the stack, players cannot cast other spells or activate non-mana abilities. However, Split Second only applies after Krosan Grip is cast — it does not prevent you from casting Krosan Grip in response to something else.

When an opponent activates an artifact's ability, it goes on the stack (CR 602.2). You then receive priority (CR 116.2b) and may cast Krosan Grip targeting the artifact. Krosan Grip now sits on top of the stack above the activated ability. Because of Split Second, your opponent cannot respond with spells or non-mana activated abilities (CR 702.61b), so they cannot easily save the artifact.

When Krosan Grip resolves, it destroys the artifact. The activated ability is then left on the stack but its source is gone. Unless the ability requires the source to be present at resolution (most do not — abilities exist independently once activated, per CR 112.7a), the ability will still resolve — but the artifact is already destroyed.

Concrete example: Your opponent activates Voltaic Key targeting a Grim Monolith (both go on the stack). You cast Krosan Grip targeting Grim Monolith. Split Second locks your opponent out of responding. Krosan Grip resolves, destroying Grim Monolith. Then Voltaic Key's untap ability resolves, but Grim Monolith is already in the graveyard, so the untap effect does nothing relevant.

So yes — Krosan Grip is an excellent answer to artifacts with activated abilities, as Split Second prevents your opponent from using tricks to save the artifact in response.