Hemel arrived at Treyew clear league leaders and by the end of the afternoon were 14 points ahead of second placed Chesham United at the top of the Calor League Premier Division.
The game was all but over as a contest as early as the 20th minute with the visitors' skipper Jordan Parkes helping himself to a quick-fire hat-trick. His first, after just two minutes, with a low hit drive, his second direct from a free-kick and his third after City had failed to clear the danger.
However, who knows if things might have been different if Ben Watson had made more of a glorious opportunity to equalise after four minutes. The striker just wanted a second too long, and it was just enough of a delay for Hemel's defender Moussaka Diarra to get in a vital challenge.
Almost immediately after conceding the third, 'keeper Grant Fisher left the action, injured with a hip problem he has been trying to shake off since Boxing Day. Fortunately, Ollie Chenoweth had been named on the sub's bench and so it was a straight swap, and the replacement was soon into the action as Lewis Toomey came so close to making it 4-0!
However, Toomey had the last word in the first half when he flicked home from close range after another Hemel corner caused trouble.
Liam Eddy stayed out during the half-time break to warm-up and was introduced in place of midfielder Ollie Brokenshire for the restart and soon caused some problems for the visitors with a shot blasted over the bar, an effort blocked and a header saved. His striking partner Watson also got in on the act but couldn't make more of a good chance.
However the noticeable difference today between the two sides were the way Hemel made the most of their chances, confirmed by Toomey making it 5-0 after 67 minutes with good finish after a teasing run, and then completing the second hat-trick of the afternoon for The Tudors
There was still time for the City diehards to enjoy a moment before the end of the afternoon however when Eddy easily tapped home a Jordan Copp left wing cross.
Truro City: Fisher (Chenoweth 22); Tully, White, Kendall (capt), Pugh, Broad, Cooke, J Lowry, Watson, Brokenshire (Eddy 46), Green (Copp 72). Subs not used: Daw, Afful.
Goal: Eddy 82.
Hemel Hempstead Town : Walker, King, Blackett (Connolly 67), Parkes (capt), Murphy, Diarra, Talbot, Thorne, Pearce, Allen, Toomey (May 81).
Subs not used: Mackey, Tokarczyk, Hutton.
Goals: Parkes 2, 15, 19 Toomey 44, 67, 81.
Crowd: 253
Referee: Andrew Bennett