Geneva was ranked the world's seventh most expensive city in which to rent a three-room apartment, and was found to be the third most expensive city in Europe, behind London and Moscow.
A year earlier, the French-speaking lakeside city was the 10th most expensive globally for rent, and seventh at the European level.
Zurich followed close behind as it too climbed the global rankings, from 20th in 2010 to 12th in 2011. Switzerland's most populous city was the fifth most expensive place to rent in Europe.
ECA reached its conclusions by comparing rental prices for three-room apartments with approximately 80 square metres of floor space. The performance of Swiss cities was affected by the strength of the franc, ECA said.
"In Zurich, the price of renting a three-room apartment reamined stable in Swiss francs in 2011, but converted into euros we noted an increase for the year of 15 percent," said ECA spokesman Frédéric Franchi in a statement.
According to the Mercer Cost of Living Survey conducted for 2011, which compares prices for some 200 different items, Geneva was ranked the fifth most expensive city in the world, with Zurich seventh.
Despite the higher costs, the Mercer Quality of Living 2011 survey showed Zurich and Geneva as second and eighth best cities to live in worldwide. Factors analysed in this survey included political, environmental, economic, health, education and transport.
ECA 2011 world rankings based on price of three-room apartment: