The champions were superior all over the pitch and a first-half total of 1-3 from Ultan Duggan deservedly earned him the man-of-the match award.
Cork senior star Tom Kenny was also in sublime form while every one of the Grenagh forwards scored in the opening 15 minutes.
Grenagh played against a stiff breeze but registered the opening scores through Dean Dalton and Seamus Coleman. Kenny was causing the Donoughmore defence serious problems and he set up Ultan Duggan for the opening goal after 20 minutes. Grenagh powered forward at every opportunity and points from Seamus Coleman, Ultan Duggan, and Conor Fitzgerald ensured they led 1-12 to 0-6 at the break.
Kenny landed a classy point and was rather fortunate to see his speculative delivery go all the way to the net in the opening minutes of the second half.
Donoughmore’s Shane Sexton worked tirelessly and his long-range delivery was kicked to the net by substitute Gerard Buckley for a consolation goal after 48 minutes.
Shane Healy also chipped in with a few nice scores during a very tough afternoon for his side.
Scorers for Grenagh: U Duggan 1-4, T Kenny 1-3, C Fitzgerald 0-5, D Dalton 0-2, S Coleman 0-2, N Doherty (f), S Burke 0-1 each.
Scorers for Donoughmore: S Healy 0-4 (0-1f), G Buckley 1-0, C O’Callaghan 0-3 (0-1f, ‘65), S Sexton 0-2 (0-1 ‘65).
GRENAGH: M Kenny; K O’Neill, P McCarthy, T Buckley; DD Dorgan, G Russell, K Cummins; N Doherty, C O’Neill; S Bourke, T Kenny, D Dalton; C Fitzgerald, S Coleman (c), U Duggan.
Subs: M Barry for D Dalton (48).
DONOUGHMORE: K Cullinane; A O’Brien, V O’Connor, A Twomey; K Horgan, A Corkery, L Barry; S Sexton, M Foley; S Healy , A Savage, C O’Callaghan; W Murphy, P Buckley, M O’Connor (c).
Subs: C Kelleher for P Buckley (29), J Twomey for C O’Callaghan (h-t, inj), G Buckley for M O’Connor (59).
Referee: J Horgan (Gleann Na Laoi).