Left-arm pacer Unnikrishnan Manukrishnan scalped six wickets for 37 runs to single-handedly demolish Tripura.
Following on, Tripura were 70 for three in the second innings, still trailing Kerala by 203 runs with a full day's play remaining in the match.
Kerala's Sandeep Warrier followed up his three-wicket haul in the first innings with two more strikes in Tripura's second essay.
Out-of-favour India pacer S Sreesanth picked up the other Tripura wicket to fall in the second innings.
Brief Scores:
Kerala: 400 all out in 131.4 overs
Tripura: 127 & 70 for three in 47 overs (Abbas Ali 24 not out, Samrat Singha 22; Sandeep Warrier 2/16).
