Can I use my Capital One Platinum card outside the U.S.?

You can use your Capital One Platinum outside the U.S.

It's a Mastercard, so it works pretty much anywhere in the world. In addition to that, you won't have to pay a foreign transaction fee when making purchases abroad, so it's ideal.

Please note that the standard cash advance fee will still apply if you want to withdraw money from a foreign ATM with your Capital Platinum card. That fee is $10 or 3% of the amount of each cash advance, whichever is greater, and you’ll also start getting charged interest right away. Plus, the ATM may be charging its own processing fees on top of that.

Bottom line, try not to use your card at ATMs because it's extremely expensive. Try to use your card directly for purchases.