Hong Kong is the most expensive city in the world for an expatriate professional migrant to live in 2016.

The top ten most expensive cities in the world comprise three from Asia-Pacific (Hong Kong (1); Singapore (4); Tokyo (8)), three from Africa (Luanda (2); Asmara (3); Kinshasa (10)), three from Europe (Zurich (5); Geneva (6); Oslo(7)), and one from America (Hamilton(9)).

In Hong Kong the very high cost of housing and healthcare, as well as the strong Hong Kong dollar which is fixed against the US Dollar, are the main reasons for it being the world’s most expensive city.

Luanda in Angola is the second most expensive city in the world for expatriate professional migrants to live. As opposed to Hong Kong, everything in Luanda is expensive as almost all international standard goods and services are imported.
http://www.xpatulator.com/cost-of-living-article/International-City-Cost-of-Living-2016-for-Expatriate-Professional-Migrants_688.cfm