The generation of acid under mechanical force is potentially useful for initiating proton-catalyzed changes in polymeric materials. Here we demonstrate that oxime sulfonates-known photoacid generators-are also acid generators when activated mechanically. NMR analysis of products suggests that the ultrasound-induced mechanochemical scission of the oxime sulfonate mechanophore also generates a ketone functional moiety, in addition to acid. Both acid and ketone moieties are useful for developing stress-responsive polymeric materials for autonomous self-healing applications.