The comic had an outburst on Twitter on Monday night (November 28) about the soap actor, who he starred alongside until as recently as last year.
Watching Cotton's behaviour in I'm a Celebrity, Thompson wrote: "Antony Cotton - the truth will out.
"Antony you nasty piece of work you are doing yourself no favours."
When asked what Cotton had been like to work with on the ITV1 soap, he added: "Trouble with a capital T."
He went on to retweet another user, who commented: "Antony Cotton. What a Miserable old fadge. Time he left the jungle."
I'm a Celebrity continues tonight (November 30) at 8.30pm on ITV1.
> Emily Scott voted off 'I'm a Celebrity'
> 'I'm a Celebrity' Fatima Whitbread, Antony Cotton in angry spat