Adam Milne and Darren Stevens took three wickets each but were unable to shift Cameron Bancroft who carried his bat for an unbeaten 206 on the second day of the Specsavers County Championship match at Bristol.
Gloucestershire were eventually bowled out for 385 as the 24-year-old Australian shared a last-wicket stand of 111 with Matt Taylor (36) and batted for more than eight and a half hours, facing 393 balls and hitting 23 fours and a six.
Bancroft’s score was just five short of his best, the 211 he made for Western Australia and the first time he had reached three figures in two spells with Gloucestershire.
By the close of a day’s play, which did not start until 1.30pm because of rain, Kent had replied with 60 for two, losing opener Sean Dickson for 20 and nightwatchman Adam Milne for a duck.
Gloucestershire had resumed their first innings on 242 for five and soon plunged into trouble as Darren Stevens (three for 50) sent back Jack Taylor lbw and Kieran Noema-Barnett, whose stumps were scattered as he pushed forward.
Adam Milne (three for 91) then struck twice in an over to remove Josh Shaw and Liam Norwell, leaving the hosts 274 for nine and in grave danger of wasting Bancroft’s efforts.
The opener had begun the day on 124 and was still short of the 150-mark when last man Taylor, with a top score of 32 not out against Essex at Chelmsford in 2014, walked to the wicket.
Together they frustrated the Kent attack and ensured Gloucestershire of a meaningful total. Bancroft picked his runs carefully to protect his partner and Taylor survived a slip chance to Sean Dickson as their stand gathered momentum.
When it reached 77 it became a Gloucestershire record for the last wicket against Kent, beating the partnership put together by Norwell and Tom Smith at Canterbury in 2014.
But Bancroft and Taylor were far from finished and Bancroft moved to his double hundred with a three through the off-side off Mitchell Claydon.
It was Claydon who finally ended Kent’s misery as Taylor was caught at short extra cover by Daniel Bell-Drummond. Bancroft had not given a chance in a tremendous display of concentration and every fielder moved to shake him by the hand as he left the field.
Kent were left with 20 overs to bat in bright sunshine. Liam Norwell soon switched ends to the Pavilion side of the ground as he sought to add to his 56 Championship wickets this season.
But it was Josh Shaw, in his second loan spell from Yorkshire, who made the breakthrough from the Ashley Down Road End as Dickson edged to wicketkeeper Gareth Roderick.
The visitors sent in Milne with four overs remaining, only for Shaw to remove him too, thanks to a low catch at first slip by who else but Bancroft.