Can I use my Credit One Platinum card in Europe without a PIN?

You should be able to use your Credit One Platinum card in Europe without a PIN basically everywhere that takes plastic, with the exception of automated payment machines, such as the kiosks in train stations and self-serve gas pumps, which only accept chip-and-PIN cards.

The fact that this card uses chip and signature security is not the main reason why you should question bringing it abroad, however. It charges a foreign transaction fee on any purchase that is processed outside of the United States, which could significantly inflate the cost of your trip.

You should still make sure to have a credit card when traveling, though, both for security and because credit cards charge far lower exchange rates than you'd get when exchanging actual U.S. dollars for Euros at a bank or airport kiosk. None of Capital One's credit cards have foreign transaction fees, for example, which means the Capital One Secured and the Capital One Platinum could be better options.