Narrative:

We were leveled at either FL300 or FL320; I cannot remember exactly which; and just about probably 50 to 80 NM east of zzzzz waypoint. My first officer needed to use the rest room. He called the crew and within minutes; the flight attendant entered the cockpit and the first officer stepped out.I was placing my mask on when I realized that something just didn't sound right. Specifically; when I first pulled the mask out of the stored position. There was no hissing sound or any flow of oxygen. I pulled up the oxygen page and realized that all cockpit crew oxygen was completely depleted. At that point; I did not want to alarm or panic the flight attendant that was currently in the cockpit.I waited for my first officer to return and requested from ZZZZ control to descend to FL250. I also requested that the relief pilot return to the flight deck. I got a hold of dispatch to inform them of our situations and diversion options. At this point; I had already informed ZZZZ control sector that we were working on an issue with the aircraft. I told dispatch that due to our current aircraft status; we couldn't continue and needed to divert. I mentioned I was looking at ZZZZ1 and ZZZZ2. The dispatcher informed me that those two airports could only be used for emergency purposes only. I confirmed with dispatch that I would [be advising ATC]; at that point; we both agreed on ZZZZ1.I was very comfortable with ZZZZ1 because both myself and the first officer had been there in the past and runways and facilities were adequate for our aircraft and passengers. Shortly after [advising ATC] we were asked to squawk 7700 by air traffic control. We were vector to a 15 to 20 mile final for runway xxc. We relayed to ATC the souls on board of 248 and a total fuel on board of approximately 110;000 [pounds] of fuel. The landing waiting at touchdown was 397;000 pounds. The landing was were smooth and rollout was uneventful. Emergency personnel followed the aircraft to the remote stand. The emergency personnel inspected the landing gear we were given the all clear. I believe that from a CRM prospective; we all (flight crew; dispatch; maintenance; ATC; and emergency personnel) worked well together inside and outside the cockpit to get the aircraft safely on the ground.

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Original NASA ASRS Text

Title: B767 pilot crew reported at cruise they discovered the crew oxygen system was empty.

Narrative: We were leveled at either FL300 or FL320; I cannot remember exactly which; and just about probably 50 to 80 NM east of ZZZZZ waypoint. My First Officer needed to use the rest room. He called the crew and within minutes; the Flight Attendant entered the cockpit and the First Officer stepped out.I was placing my mask on when I realized that something just didn't sound right. Specifically; when I first pulled the mask out of the stored position. There was no hissing sound or any flow of oxygen. I pulled up the oxygen page and realized that all cockpit crew oxygen was completely depleted. At that point; I did not want to alarm or panic the Flight Attendant that was currently in the cockpit.I waited for my First Officer to return and requested from ZZZZ Control to descend to FL250. I also requested that the Relief Pilot return to the flight deck. I got a hold of Dispatch to inform them of our situations and diversion options. At this point; I had already informed ZZZZ Control Sector that we were working on an issue with the aircraft. I told Dispatch that due to our current aircraft status; we couldn't continue and needed to divert. I mentioned I was looking at ZZZZ1 and ZZZZ2. The Dispatcher informed me that those two airports could only be used for emergency purposes only. I confirmed with dispatch that I would [be advising ATC]; at that point; we both agreed on ZZZZ1.I was very comfortable with ZZZZ1 because both myself and the First Officer had been there in the past and runways and facilities were adequate for our aircraft and passengers. Shortly after [advising ATC] we were asked to squawk 7700 by air traffic control. We were vector to a 15 to 20 mile final for Runway XXC. We relayed to ATC the souls on board of 248 and a total fuel on board of approximately 110;000 [pounds] of fuel. The landing waiting at touchdown was 397;000 pounds. The landing was were smooth and rollout was uneventful. Emergency personnel followed the aircraft to the remote stand. The emergency personnel inspected the landing gear we were given the all clear. I believe that from a CRM prospective; we all (flight crew; Dispatch; Maintenance; ATC; and emergency personnel) worked well together inside and outside the cockpit to get the aircraft safely on the ground.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.