An implantable device and associated method detect anodal capture during electrical stimulation. A first pacing pulse is delivered using a first cathode and a first anode. A second pacing pulse is delivered using the first cathode and a second anode. A first response to the first pacing pulse and a second response to the second pacing pulse are measured. Anodal capture of the first pacing pulse at the first anode is detected in response to a first difference between the first response and the second response.