Gykeye Edwards, known as Sandy, aged 61, was last seen yesterday (4/8) in Addington Road at about 12pm.
When he was last seen, he was wearing a blue and yellow checked short and navy blue jeans.
Sandy is believed to have been in the Newbury and Whitchurch areas today (5/8) driving a blue Renaul Scenic with a registration plate beginning NX06.
Investigating officer Inspector Chris Clayton-Brown, based at Loddon Valley police station, said: “I would like to hear from anyone who has seen Sandy, or anyone matching his description, as we are concerned for his welfare.
“If you have any information which you think could help us to find Sandy, please call us on 101, quoting reference 43180238310.”