The poll surveyed 18- to 34-year-olds in 10 developed countries, including the United States, Britain, France and Australia.
The responses varied significantly across the countries. While 56 percent of those polled in the United states had a favorable take on Snowden, the number was much higher in continental Europe, reaching 78-86 percent.
Despite that, the governments of Canada, France and the Netherlands are attempting to expand their abilities to spy on civilians, the ACLU said.
Snowden's revelations could cost him as many as 30 years in prison in the United States, where he is wanted on charges of espionage and theft of government property.
On August 1, 2013, Russia granted the whistleblower temporary asylum for one year. In August 2014, Snowden received a three-year residence permit in Russia.