B737-700
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Weight And Balance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Hazardous Material Violation
General None Reported / Taken
Human Factors
ZZZ loaded HAZMAT material; an aircraft battery; onto my flight without informing me or Dispatch; and also failed to present me with the Dangerous Goods form before departure. I had no idea it was onboard until I arrived in ZZZ1 and was asked to post sign the Dangerous Goods form after completing the flight. I refused to sign it and notified my Dispatcher and the Chief Pilot.
When we arrived at the gate in ZZZ1; an Agent boarded the aircraft and asked the Captain to sign a NOTAC.  The Captain explained that we were never made aware of any HAZMAT prior to or during the flight.  Evidently; we transported HAZMAT without being notified of it being onboard. The Captain was not able to sign and we didn't carry the required documentation. We were also unable to notify Dispatch and have the HAZMAT remark listed on the Dispatch Release per Company policy.
Air Carrier flight crew reported the transport of undeclared Hazmat. Dispatch failed to provide flight crew the required Dangerous Goods Form prior to gate departure. Captain informed Chief Pilot and Operations upon arrival.