Declan Connell set the pace as day one opened at Donington Park as he beat Cameron Hall by 0.395secs with a best lap of 1min 46.152s.
As the weather brought a damp and overcast start to the action, Dan Brooks was third quickest, just ahead of Lewis Jones as Aaron Silvester rounded out the top five.
Pirelli National Junior Superstock Championship with MotoNovo, Donington Park, FP1:
1. Declan Connell (DC Racing) 1min 46.152s
2. Cameron Hall (Triple M Vehicle Sales) +0.395s
3. Dan Brooks (R4R Vision Team) +1.370s
4. Lewis Jones (Lewis Jones Racing) +2.196s
5. Aaron Silvester (A&J Racing) +3.549s