Update March 2017: Discover has become nearly unusable in China. If you do not have the newer chip version you may experience success, however the chip cards are rejected at almost all merchants except those that otherwise accept many foreign credit cards. I have repeatedly sent feedback to Discover and gotten no helpful response. One representative said sometimes in her experience terminal require 3 failed attempts with a chip before accepting the magnetic strip swipe. Fat chance getting someone to swipe over and over in China!
In December I wrote Is Discover the best credit card for China? because of its link-up with China’s UnionPay which allows reciprocal access on each others’ payment networks.
I got around to acquiring a Discover card in June and have been testing in China. As with others’ experience, the card is indeed accepted at UnionPay locations, which is everywhere a card is accepted in China, however the challenge is getting incredulous clerks to swipe the card. They reflexively look for the UnionPay logo, and not seeing it, either return it or give a puzzled look, thinking it a regular foreign-issued card that is accepted at very limited locations.
Unless you speak Chinese, the best bet is to carry Discover’s printout card. If you don’t have that, try pointing to a UnionPay logo on the door or counter if there is one.
There is no foreign transaction fee.
If you are really in a bind and need a cash advance, that is possible with a pin, which you can obtain on the Discover website.
For more detail, see Discover’s Asia FAQ.
I had a much more mixed experience in Japan with Discover’s JCB partnership. Discover’s FAQ with regard to China says, “You can use your card anywhere you see the Discover acceptance mark or the China UnionPay acceptance mark throughout mainland China.” However for Japan, “You can use your card anywhere you see the Discover acceptance mark and at almost all locations you see the JCB acceptance mark throughout Japan. This includes: hotels, restaurants, airport limousine transportation service, airport shopping and dining and many more locations.” (emphasis added). Indeed.