After rain had delayed the start of the second day until after tea, he and Darren Robinson progressed from 72 to 194 without loss to leave the title-chasers just 86 runs adrift.
The England selector had started the day on 33 and was soon driving with his customary power and assurance to complete his half-century with the help of 10 boundaries. He was to gather another five fours and a six to complete his hundred which arrived off 162 deliveries.
Robinson also went for his shots in helping the 43-year-old Gooch put together the county's best opening partnership of the season and he had reached 72 by the close. Gooch's century was his 92nd for Essex and his eighth at the Colchester ground.
Ashley Giles and Tim Munton broke a 66-year-old Warwickshire record with a last wicket partnership of 141 on a rain-shortened second day against Worcestershire at New Road.
Giles made a career-best 83 and Munton reached a maiden championship half-century in wiping out the previous record of 128 set by Fred Santall and Wilf Sanders against Yorkshire in 1930.
Munton collected eight fours and a six off 131 balls during only the fourth century stand for the last wicket in Warwickshire's history.
They were eventually dismissed for 310 but Worcestershire faced only 7.4 overs, reaching 10 without loss, before rain finished play for the day in mid-afternoon.
Carl Hooper, the West Indian batsman, became the first Kent batsman to reach 1,000 runs in the championship this season during his innings against Glamorgan at Cardiff.
Hooper passed the milestone to reach 38 and celebrated by hitting Neil Kendrick out of the ground and into the River Taff for six. It was the highlight of another rain-ruined day as the title contenders closed on 255 for 3 but still with a great deal to do if the weather relents.Reuse content