His surprise departure was revealed in a Companies House filing yesterday.
Mr Wilson, giving his first interview in April after his 25-year career with Murray International, told The Herald he hoped to "double the size of the business over the next three to five years".
He had staged the buyout four months earlier with two executive colleagues and the backing of buyout specialist Dunedin, which has partner Dougal Bennett on the board.
In March, the group appointed as chairman Maurice McBride, a non-executive at Dominion Gas and Alexander Ross Holdings and previously a non-exec at Air Energi and Sparrows Group.
Mr McBride said last night: "I can confirm that Donald Wilson has stepped down from his role as CEO of Premier Hytemp.
"Donald is a strong leader and a talented manager.
"He has done a good job at Premier Hytemp and we wish him well for the future."
He said the group was "focused on expanding its capabilities, geographic footprint and product offering to enhance its position as a global leader" and would appoint "a new CEO with the international experience to lead the company through this process".
Mr Wilson said: "Having successfully steered the business through a difficult turnaround and achieved an exit from the Murray Group ... I feel the time is now right for me to move on.
"I have a number of interesting projects in the pipeline which I am looking forward to pursuing."