The classic rock and speech station will reach a potential audience of 1.8 million adults.
Music on the station will include everything from Led Zeppelin to U2 and will be interspersed with high levels of daytime speech, including local news, current affairs and interactive debate.
Rock fans will also be able to hear live concerts and specialist rock shows on the station. The older target audience is not a new concept for GMG Radio, which recently bought Saga Radio's four licences and will relaunch them next month, together with its two Smooth FM stations, as stations aimed at the over-40s.
RockTalk brings GMG Radio's number of stations to 13 and will be the group's third in the North West, after 105.4 Century FM and 100.4 Smooth FM. In January, GMG launched Rock Radio in Scotland, after its purchase of Q96 from UTV last year.