Barcelona, which has already taken action to stop the spread of holiday rental apartments, is the latest Spanish city to see protests for cheaper housing.
Backed by left-wing parties and unions, the demonstrators gathered in central Barcelona behind a giant banner declaring "Lower the rents".
"Today a new political cycle starts concerning housing," Carme Arcarazo, spokesperson for the Catalan Tenants Union, the main organiser, told reporters.
"Investors must not be allowed to come to our cities and play with the apartments like a game of Monopoly," she added.
The union would target "profiteers" who are taking "half of our salaries", Arcarazo said.
The demonstrators demanded a 50 percent cut in rents, leases with an unlimited term and a ban on "speculative" sales of buildings. They threatened to start a rent strike.
An estimated 22,000 people took part in a similar demonstration in Madrid on October 13. Campaigns have been launched in other cities.
According to the Idealista specialised website, rental prices per square metre have risen 82 percent across Spain over the past decade.
The average salary has gone up by 17 percent in that time, according to the national statistics institute.
Facing pressure over a housing crisis, the government in 2023 passed legislation calling for more social housing, greater restrictions on rents in high demand areas and penalties for owners who do not occupy properties.
But rents have continued to rise while the government has battled city and regional authorities to get some parts of the law applied.
