Widnes (8) 26
Tries: Leuluai, Tyrer 2, Varkulis, Ropati Goals: Tyrer 3
Hull FC (22) 50
Tries: Whiting, Sharp, Horne 2, Westeman, Lauaki, Briscoe 2, Phelps
Goals: Tickle 4, Westerman 3
Hull FC reached the last eight of the Challenge Cup as they overcame a spirited Widnes at the Stobart Stadium.
Next year's returning Super League outfit Widnes ran in five tries through Steve Tyrer (2), MacGraff Leuluai, Richard Varkulis and Tangi Ropati.
But Richard Whiting, Will Sharp, Richard Horne and Joe Westerman all crossed before the break for Hull.
And Tom Briscoe (2), Epalahame Lauaki, Horne and Cameron Phelps added five more in the second half.
The visitors led from the ninth minute to the final whistle, but were unconvincing, despite their nine tries.
And they were given a tougher contest than they might have expected by a side they will play in Super League next season.
Widnes were without Wigan trio Logan Tomkins, Dominic Crosby and Joe Mellor, who are all on dual registration deals but not eligible in the cup.
They rarely looked like springing a shock, but they were competitive throughout and trailed only by 12 points with as many minutes remaining.
Hull coach Richard Agar:
"It was mission accomplished but the first thing I should probably do is pay tribute to Widnes.
"They are not having the best of seasons by their standards in the Championship but they turned up today and were very tenacious. Perhaps the final scoreline didn't do them enough justice.
"You can look at the points total being 50 or you can look at the overall performance. We probably weren't prepared to work hard enough when we didn't have the football.
Widnes coach Denis Betts:
"If you turn up with that attitude and application week in, week out, then we can only get better. That is what has been lacking.
"They know exactly what they are supposed to do but that has been squashed by a bit of anxiety and pressure. They pulled the shackles off a bit today, as they had nothing to lose.
"Sometimes you see a really competitive game but then look at the scoreline and say, 'How's that happened?' I think that's what's happened today."
Widnes: Flynn; Penny, Ropati, Tyrer, Gardner; I'Anson, Coyle; Pickersgill, Lunt, Kavanagh, K Haggerty, Leuluai, Allen.
Replacements: Varkulis, Grady, Gore, D Sculthorpe.
Hull: Phelps; Sharp, Whiting, Yeaman, T Briscoe; Turner, Horne; O'Meley, Houghton, Moa, Manu, Westerman, Tickle.
Replacements: Radford, Washbrook, Lauaki, Dowes.
Referee: Rob Hicks (Oldham).