Essex 106 for 0 (A Cook 64*, Browne 31*) trail Kent 207 (Compton 47, S Cook 3-19) by 101 runs
Earlier, Kent elected to bat on a green-tinged pitch under heavy grey clouds that required the use of floodlights after an hour. Their innings lasted just short of two sessions for 207 as the lower-order threw away their wickets with some abandon.
Twanda Muyeye survived a decent chance to Matt Critchley at third slip before he was beaten for pace to present Sam Cook with the first of three wickets for 19 in 11 overs.
Next ball Joe Denly's miserable season continued when he played down the wrong line and was caught behind for his fourth duck of this campaign.
To compound Kent's problems, Harry Finch faced 15 deliveries without scoring when he set off for a non-existent single to gully where Paul Walter swooped and hit the single stump he could see.
Compton and Leaning settled in for a stand that needed 17 overs to put on fifty, and that despite Compton hitting Doug Bracewell for three successive boundaries, two through the covers, the other a flick off his legs.
However, to the last ball before lunch Compton attempted to dig out a fuller delivery from Simon Harmer and only succeeded in chipping the ball back tamely to the bowler.
Leaning followed soon after the break when he got a thick edge to one from Sam Cook that went away from him and wicketkeeper Adam Rossington took a fine diving catch to his right. Joey Evison went shouldering arms to one that came back late from Bracewell.
Grant Stewart smashed Harmer for two straight sixes in a brisk, seven-over stand of 43 with Jordan Cox before Porter found a peach of a ball to remove Cox.
Porter then set a short-ball honey-trap for Stewart who hooked straight to one of an army on the boundary, and two balls later Matt Quinn skied rashly to midwicket. Arshdeep Singh swept Critchley for a huge six and wafted lazily at the next ball and was stumped without bothering to look back.
When Essex replied in the evening session, Alastair Cook slipped into imperious mode after a watchful start, showing an array of shots around the wicket in depositing Stewart for three successive fours, though he was put down off the same bowler to a sharp chance in the gully.
Of the fifty partnership in 17 overs, hecontributed 38 with Browne playing second fiddle with a dozen; of the century partnership Browne had 27 and Cook 63, passing fifty for the fifth time this season when he swept Hamid Qadri for his 10th boundary.
Essex, incidentally, will be reinforced with the inclusion of Dan Lawrence in their batting line-up on day two as he returns south after being the spare man in the England XII for the concurrent fourth Test at Old Trafford. He will replace Robin Das.