Former Channel 4 racing pundit John McCririck is seeking £3m in damages - claiming he was axed by the broadcaster due to his age.
The 72-year-old presenter was among a number of faces axed by the channel after it awarded the production contract to IMG Sports Media, ending its previous agreement with Highflyer.
McCririck spoke out last October at the time of the decision, which he blamed on ageism.
He has now issued a statement setting out his case: "Channel 4 and production company IMG Sports Media were yesterday each served a letter before action for age discrimination.
"After 29 years with Channel 4 Racing, on a rolling annual contract, I have been sacked without any consultation or cogent explanation. I am 72.
"For loss of future earnings, unfair career damaging, public humiliation, stress and mental anguish, I will be seeking £500,000.
"Ageism is illegal. For tens of thousands of employees it has become the feared scourge of our society.
"This litigation should prove to be a watershed. There's no upper limit to the amount of damages employment tribunals can award under the Equality Act 2010 .
"I am seeking a further exemplary, punitive £2.5m, part of which will be donated to charitable organisations helping to prevent negative prejudice in the workplace."
McCririck said he was being represented on a no-win no-fee basis by employment and sports law specialist solicitor Stephen Beverley, of the London West End Cavendish Legal Group.