The Daily Mail says the experienced German has impressed while on trial at Loftus Road.
He is currently a free agent after leaving Fulham last summer, after a series of hip, shoulder and ankle injuries.
The 27-year-old played for the reserves on Tuesday in their 3-0 defeat against Reading.
Volz will be boss Mick Harford's fifth signing at the club since replacing Paul Hart last month.
Writing on his blog recently, Volz said: "I’m very grateful they’re giving me the opportunity to build up my match fitness after such a long time out.
"You can train all you like but it's matches you need to really get back to your best."