Having a passport which is valid for at least 6 months after the end of your trip is compulsory before you could apply for a visa to enter Cambodia.

Visa on arrival is convenient and no prior paper work or approval is needed. It is possible to obtain a visa on arrival at the international entry points into Cambodia as follows:
 
Airports :
Phnom Penh International Airport
Siem Reap International Airport
 
Cambodia-Vietnam border :
Bavet International Check Point
Kha Orm Sam Nor International Check Point
 
Cambodia-Thailand border
Cham Yeam International Check Point
Poi Pet International Check Point
O’Smach International Check Point

 Application for an entry visa on arrival includes:
 A completed visa application form
One recent photograph (4x6)
Visa fee
Supporting documents for business and official visas
 
Visa fees
USD20 for a Tourist Visa
USD25 for a Business Visa
 
Visa exemption
The nationals of Laos, Malaysia, the Philippines and Singapore are exempt from visa for stays of up to 30 days.

A Tourist Visa can be extended only once for up to 30 days with single entry, while a Business Visa can be extended for 01, 02, 03, 06 or 12 months with multiple entries.

Disclaimer: The information hereabove is for your reference only and subject to change without prior notice. For the most up-to-date information, please check with the Cambodia Minitry of Foreign Affairs and International Co-operation.