Declan Connell set the pace as the Junior Superstock machines hit the track at Knockhill for the first time, clocking a 51.486sec lap to hold off Oliver Barr by 0.020secs.
Louis Valleley ended the session a further 0.197s behind in third place, setting an identical lap time of 51.703s to fourth-placed Aaron Silvester. Owen Mellor rounded out the top five.
Pirelli National Junior Superstock with Santander Consumer Finance, free practice one:
1. Declan Connell (DC Racing) 51.486s
2. Oliver Barr (3B Construction) +0.020s
3. Louis Valleley (Team Val-Tech Racing) +0.217s
4. Aaron Silvester (A&J Racing) +0.217s
5. Owen Mellor (Team Mellor Racing) +0.274s