Rob Key registered an unbeaten century to help ensure Kent made a promising reply to Hampshire's first innings total of 405-9 declared on day two at Canterbury.
In the field for more than four sessions, the hosts performed well with the bat when their turn came and finished the day at 200-1 with Key undefeated on 105 not out.
The former England batsman lost opening partner Sam Northeast (eight) with only 37 on the board, but then teamed up with England Under-19 starlet Daniel Bell-Drummond to add an unbroken 163 for the second wicket through to the close.
Key, who won the last of his 15 Test caps in 2005, batted faultlessly to reach his century from 142 balls and with a dozen boundaries.
At the other end, rookie Bell-Drummond, in only his 11th championship start, made a sticky start and looked troubled by the pace of James Tomlinson. But, after surviving the left-arm paceman's new ball burst, Bell-Drummond relaxed into his work and by stumps had reached 74 as he and Key took Kent to their first batting bonus point of the match.
At the start of the day, Hampshire elected to extend their first innings beyond lunch before finally declaring nine wickets down and some 30 minutes into the mid-session.
After his stoic, opening day century, former Kent batsman Michael Carberry eventually departed for 154 as he chased a wide one from Calum Haggett to be caught behind.
After lunch, Kent skipper James Tredwell took his first wickets of the championship campaign on Kentish soil to finish with respectable figures of 3-83. The off-spinner had Ervine stumped for 72, Sohail Tanvir (32) caught at slip then Danny Briggs (19) caught at long on to spark the Hampshire declaration.