Ian Charlesworth alleges he was the victim of bullying, intimidation, harassment and victimisation by John Briffitt and Tim Pape at the Shaw Trust.
His claims will be heard by an independent lawyer on 19 September.
Charlesworth was dismissed on 30 July, five days after warning trustees that Briffitt and Pape's plans to expand the charity's employment services into Australia were too risky and could jeopardise the charity's finances (20 August, page 3). He wants reinstatement.
Rowena Hayward, an organisation officer for the GMB union, which is representing Charlesworth, said the trust had delayed releasing documents relevant to the case.
Catherine A'Bear, chief officer for corporate affairs at the trust, said: "We don't comment on individual HR matters."
- See Editorial, page 12.