Martinez signed for the Bucks in July 2017, principally as understudy to another former Solihull keeper, Jasbir Singh.
The tall shot-stopper has previously spent time with Bedworth United, Hereford United and Sporting Khalsa as well as Moors.
Solihull have also announced that Jamey Osborne's loan has been extended until the 26th January.
In his time back at the ATG Stadium, Osborne (pictured) has been heavily involved in Moors` better performances of late, and he has agreed, with parent club Grimsby Town, to stay for another month.