You may be able to use a debit card but they'll need to be able to put a large hold on funds. I ran into this years back when I graduated college; I had a credit card, but it was secured, and the amount the rental car agency wanted to put on it, outside of the fees (the actual fees were being paid for by my place of employ as part of my relocation package) was too high to put on the card, and they refused to rent me anything. I still refuse to use that rental car company to this day.