Nationals of Australia, Germany, Israel, New Zealand, Republic of South Africa, Sweden, United Kingdom, and United States of America are issued a visa upon arrival that is valid for a period up to 30 days. Have your passport and payment ($30) available when you land at the airport. If you wish to apply online before you travel, there is a 3-day processing time. Here is the information and online application for a single-entry visa to Rwanda.
Acceptable forms of payment are U.S. dollars (printed during or after 2006), Rwandan francs, or Visa or MasterCard credit cards. Note that is recommended to travel with cash in case the credit card machines are not functional at the time of your arrival.