Just a handful of private rental properties are available to single people on benefits, according to Crisis.
The charity for the homeless used mystery shoppers looking for a room in shared properties in Birmingham, Leeds and Lewisham, London.
Most of the properties were too expensive for those on benefits, and of those that were the right price, most of the landlords did not take benefits tenants.
For the last year, people aged under 35 who are on benefit receive the shared accommodation rate, lower than Local Housing Allowance. The age limit was raised from 25.
The research found that in Birmingham, of 1,813 shared property rooms available, just 188 were affordable, but of these, only 29 were available to benefits tenants.
In Leeds, of 1,877 rooms available, 290 were affordable, and 31 open to housing benefit tenants.
In Lewisham, a total of 670 rooms were available, of which 82 were affordable and just six open to benefit tenants.