Luanda, Angola, one of the world's poorest cities, is also the world's most expensive city for expatriates to live in 2014 according to Mercer's annual Cost of Living Survey. 

Second on the list is N'Djamen, the capital city of the central African nation of Chad. And for a $6.64 cup of coffee, make sure to check out Hong Kong, which ranks third. 

The list, which is created for people working abroad, analyzes the prices of more than 200 goods and services like housing, travel fees, schooling, food and alcohol. 

So, how did two poverty stricken cities top wealthier cities like London and Tokyo?  The answer largely has to do with the two country's heavy reliance on imports. 

"While Luanda and N'Djamena are relatively inexpensive cities, they are quite costly for expatriates since imported goods come at a premium," Ed Hannibal, Partner and Global Leader for Mercer's Mobility practice told CNBC.

Additionally, some expats are willing to pay more for the comforts they're used to.

"Finding secure living accommodations that meet the standards of expatriates can be challenging and quite costly as well. This is generally why some African cities rank high in our survey," Hannibal added. 

Also atop the list are Zurich, Geneva, Bern, Singapore, Tokyo, New York, Los Angeles, São Paulo, London, Moscow, Beijing, Seoul, Copenhagen, Tel Aviv, and Kinshasa.