@Stuart ********
That is immaterial. They should ask you to prove your Nationality before anyone will accept a reservation or booking. Anyway I get sick & tired of seeing insecure comments by people who have probably never flown to Thailand, or anywhere else on one-way tickets. I've flown into Don Meuang dozens of times before Suvarnabhum was even being built and after Swampy was opened and I have never been asked at any departing airport to produce a return, or onward travel document and I've flown into Thailand from, Hong Kong, Taiwan, mainland China, Indonesia, Brunei, Vietnam, Myanmar, Malaysia, Dubai, Abu Dhabi, Singapore, Bahrain, Nigeria, Ethiopia, UK and several other Northern European countries and never been asked by check-in to produce a return, or onward travel document or been asked by Thai immigration when entering. If people are unsure about themselves turning up at check-in without, return, or onward travel proof that is their perogative. Also on a few occasions I've flown to the UK on return tickets bought in Thailand, so why wasn't I asked as a British passport holder at check-in at the UK airports on return leg, which would then be the same as a one-way ticket why haven't you got a return ticket when flying back to Bangkok?