Lewis Jones set the pace as the Brands Hatch weekend kicked-off, leading Franco Bourne by 0.102secs with a best lap of 1min 32.892secs.
Bourne was second, with Cameron Hall third as Taylor Rose ended the session fourth, just ahead of Kam Dixon.
Pirelli National Junior Superstock Championship, Brands Hatch, FP1:
1. Lewis Jones (Lewis Jones Racing) 1min 32.892s
2. Franco Bourne (Marvel HCL Motorsport) +0.102s
3. Cameron Hall (Triple M Vehicle Sales) +0.222s
4. Taylor Rose (Taylor Rose Racing) +0.480s
5. Kam Dixon (RK Racing) +0.497s