This last 16 Scottish Cup tie got off off to a flier with four goals scored in the first 14 minutes.
Ryan McCallum turned quickly and hooked the ball over keeper Brown into the roof of the net.
Four minutes later the visitors were level when a cross from the left wing was headed clear to the edge of the box from where Gallacher slammed the ball past Penicuik keeper Billy Bald into the bottom corner of the net.
Penicuik, however, went straight up the park and a McCallum cross picked out Keith Lough who chested the ball down and volleyed the ball into the net.
Then in the 14th minute Kirkintilloch were awarded a soft penalty kick that was converted by Green.
There were no more goals scored in what was an eventful first half.
It was all to play for then in that second half and just six minutes in the visitors took the lead when Gallacher got past three Penicuik defenders, cut the ball across goal where Duff slipped the ball to McMenamin and he drilled the ball into the far bottom corner of the Penicuik net.
In the 56th minute, Penicuik’s Darrell Young received a second yellow card and an early bath.
Then a testing Neil Jancyzk cross caused panic in the Rob Roy defence when keeper Brown spilled the ball and as he tried desperately to recover the ball was eventually booted clear to safety.
Minutes later, Penicuik were under severe pressure and only a great save by keeper Billy Bald and three blocking tackles saved the day for Penicuik.
Despite Penicuik being down to ten men, in the 65th minute a Keith Lough through ball split the visitors’ defence and Lewis Barr did well under pressure to slip the ball to Ryan Gay who coolly stroked the ball home to level the amazing match at 3-3.
However it only took two more minutes for Kirkintilloch to restore their lead when Walker scored what proved to be the winning goal and Penicuik’s untimely exit from the Scottish Junior Cup.
Penicuik: Bald, Forbes, McDonald, Hume, Young, Janczyk, Connolly, Barr, Lough, McCallum (c), Montgomery. Subs: S Scott, Gay, Somerville, K Scott, Jones.