A Type O plug in Thailand?

Yes — it seats, earth and all.

your Type O
🇹🇭 Type A socket
🇹🇭 Type B socket
🇹🇭 Type C socket
🇹🇭 Type O socket
🇹🇭 Type F socket

Thailand's Type A and Type B and Type C and Type O and Type F sockets accept a Type O plug. Both sides carry an earth, so grounded appliances keep their protection. The wall delivers 220 V at 50 Hz (198–242 V within tolerance) — if your device isn't rated for that (look for "100–240 V" on the brick), an adapter won't save it.

Grid facts verified against IEC World Plugs — Thailand. Physical-fit verdicts derive from pin geometry and each socket standard's acceptance list — not safety advice.