B737-900
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Confusion; Situational Awareness; Troubleshooting
Deviation / Discrepancy - Procedural Hazardous Material Violation; Deviation / Discrepancy - Procedural Published Material / Policy
General Work Refused
Human Factors
CSA [Customer Service Agent] approached me shortly after arrival in ZZZ with a question about an item a passenger wanted to bring onboard. I went into the boarding area; to view a motorized skateboard. At first I was not to concerned; he indicated that he has had no trouble getting through security and had flown with this skateboard several times. He had flown to ZZZ1-ZZZ on (airline) with this skateboard. I returned to the flight deck; retrieved my iPad and started to research Lithium Ion batteries and found information on restrictions to carrying this skateboard on the plane. He could not remove the battery without specific tools. Long story short; I apologized and told this passenger I would be unable to put this skateboard on the airplane. The reason I'm reporting this is my concern that he was able to get the skateboard on the ZZZ1-ZZZ flight.  Get a message out to CSA and crew members to be on the lookout for these kind of items.
B737-900 Captain reported concerns regarding gate agents lack of knowledge of approved Lithium Ion powered devices on passenger aircraft.