Cambodia's currency is the riel which comes into notes of the denominations of KHR100,000, 50,000, 20,000, 10,000, 5000, 2000, 1000, 500, 200, 100 and 50. 1 US Dollar is worth about KHR 4,000.

US Dollar and Thai Baht are widely accepted in Cambodia and it's smart that you have enough US Dollar in cash while traveling in Cambodia. For small expenses such as for drinks, tipping... you may like to use Riel and others can be paid in US Dollars. You pay US Dollar for an item, the change comes back in Riel and you can accumulate Riel for future small expenses. If you are traveling in the remote areas of Cambodia, it's still necessary that you have Cambodian Riel with you since some don't accept US Dollars or Thai Baht, or if accepted then the exchange rate is very low.

The Khmers are very careful about clean money notes. When you travel in Cambodia, make sure all notes you use, be it US Dollar, Thai Baht or Cambodian Riel, are the good-shape and clean ones. If there's a tear on the note, your money won't be accepted. When you receive the cash paid back, it's good to check the notes carefully too.

Changing money is convenient as there are numerous money exchange outlets in tourist areas such as Phnom Penh and Siem Reap. At street money changers, exchange rates seem to be always better than those at a bank.

Credit & debit cards
Credit cards are not generally accepted, but can be used in upmarket hotels and restaurants in Phnom Penh and Siem Reap for payments. There are hardly ATMs in Cambodia. Cashing credit card is limited at certain banks in Phnom Penh and Siem Reap only and incurs a commission charge.
 
Traveller's cheques
Travellers cheques are not widely accepted in Cambodia and hence are generally not recommended. Still you can change travellers cheques at certain big banks in Phnom Penh and Siem Reap. The commission is about 2%. It's easier to change travellers cheques in US Dollars.
 
Banking hours
Mon-Fri 0800-1500. Some banks are open on Saturdays.
 
Money changers normally located around the markets or tourist areas in town.