When Jamie Shaul sprinted over following Bureta Faraimo brilliant run to put Lee Radford’s side ahead for the first time in the 71st minute, it seemed the Black and Whites would finally have something to celebrate.
Without a win since beating Widnes Vikings in June, they arguably would have deserved it after, with England star Jake Connor taking control, creating plenty of chances.
However, as has been too often the case in recent times, they crucially switched off at the death to allow Catalans the chance to score not once but twice.
Their right edge was undone for Brayden Wiliame to cross, Lucas Albert - having taking over kicking duties from Josh Drinkwater - missing the conversion attempt to leave it level at 20-20.
A draw would have at least ended the rot for Hull but somehow they found their middle splintered in the very next set and Kenny Edwards jubilantly raced in in the 78th minute untouched between the posts for the Challenge Cup holders.
Radford said: “I had two minutes of ecstasy at that point (Shaul’s try) which I’ve not had in the last six or seven weeks.
“It was a good two minutes.
“But you can’t be disappointed with the result when we’re defending as we are.
“When you watch the tries we conceded... the systems stuff you have to stand by.
“And the one-on-one tackles you have to make.”
Catalans - who saw Jason Baitieri put on report in the third minute for “grabbing someone’s manhood” - had lost six consecutive Super League games themselves and had not truimphed since winning at Wembley last month.
They now replace Hull in seventh with Radford’s side dropping to eighth before they round off a disappointing season at second-placed Wigan Warriors on Friday.
They had actually started in a confident manner but wasted a raft of chances early in the first half.
There was plenty of decent build-up play and three times they splintered Catalans through the middle but there was no finish.
Shaul spilled with the line begging, Fetuli Talanoa didn’t even realise Scott Taylor was on his shoulder while both Danny Houghton - switched to loose forward after an early head injury to Dean Hadley - and Jordan Lane were caught in possession on the last tackle.
As time passed, you could sense the frustration growing and then passes were forced that need not have been.
Almost inevitably, Catalans scored with their first real attack via former Hull prop Sam Moa in the 14th minute, Josh Drinkwater improving.
After a woeful and embarrassing fumble at dummy-half in his 20m area from Carlos Tuimavave, Iain Thornley should have added a second but the ex-Hull KR winger was just as bad with a painful handling error of his own.
Still, after Wiliame and Greg Bird both went close, Catalans forced a drop-out for Tony Gigot to cruise through from 4om and beat Shaul with ease.
Hull kept at it, though, and did earn some rewards when Josh Griffin touched down after Talanoa palmed down Connor’s high kick to leave them trailing 10-4 at the break.
Drinkwater, who had converted Moa’s effort, slotted a penalty early in the second period but Connor quickly got his side back in touching distance.
When Gigot spilled his high, hanging kick in front of the posts, it was the England international’s perfectly-timed short pass that sent Brad Fash over from 15m out.
Connor improved only for the French side to hit straight back, veteran Australian Bird typically to the fore as he barrelled close for his side to strike wide to Thornley who this time did hold the pass.
Still, with Connor’s steepling kicks causing them all sorts of problems, it was clear the hosts would get another chance.
Lewis Tierney dropped one and this time Connor threw out a stunning long cut-out pass for Talanoa to cross in the 63rd minute.
He could not add the extras but Tierney had to leave injured after another hugh kick from the England international had him flapping.
Connor then unleashed Griffin with another perfect pass but, for some reason, the Hull centre ignored Talanoa and floated a nonsense pass inside to no one to see another chance disappear.
They did get over when Faraimo swatted after four defenders to set up Shaul but then came that collapse.
Hull FC: Shaul; Faraimo, Griffin, Tuimavave, Talanoa; Miloudi, Connor; Taylor, Houghton, Matongo, Lane, Washbrook, Hadley. Substitutes: Fash, Litten, Paea, Bienek.
Catalans Dragons: Gigot; Tierney, Mead, Wiliame, Thornley; Albert, Drinkwater; Maria, McIlorum, Moa, Bird, Julien, Baitieri. Substitutes: Belams, Da Costa, Edwards, Goudemand.
Referee: Marcus Griffiths (Widnes)