Maybe. You, the employee, may be responsible for the unauthorized use of your business-purpose credit card by a third party. However, if you report the loss or theft before your business-purpose credit card is used by a third party, the card issuer and/or your employer cannot hold you responsible for any unauthorized charges. If the unauthorized user uses your card before you report it lost or stolen, the most you will owe for unauthorized charges is $50 per card.
These limitations on your liability apply only if a third party uses your card. If you use the card in an unauthorized manner, you are responsible for all charges.