Defence Minister Phumtham Wechayachai has named Gen Trisak Indararusmi, a former expert attached to the Royal Thai Armed Forces (RTAF) and a former classmate of former prime minister Thaksin Shinawatra, as his secretary.
The appointment of Gen Trisak, a member of Class 10 of the armed forces preparatory school, comes ahead of Mr Phumtham officially starting work at the ministry on Monday.
It is speculated Mr Phumtham will appoint Gen Worawit Chinanawin as his adviser.
The Defence Ministry will hold a welcoming ceremony for the new defence minister, which will include paying respects to sacred objects and inspecting a guard of honour.
He is expected to be briefed by military leaders after the ceremony and lay down policy guidelines for the armed forces.
Mr Phumtham, who also doubles as a deputy prime minister, said on Friday that the annual military reshuffle will be finalised as quickly as possible.
He denied it was a topic of discussion during a meeting with military leaders on Thursday, saying the meeting was an introductory discussion.
The minister insisted he would follow proper procedures in handling the annual reshuffle and make every effort to resolve any differences that may arise during the process.
"During the rotation of positions, whether it be at the Defence Ministry or elsewhere, there will be speculation, rumours and slander. It's our responsibility to screen and resolve the matters carefully," he said.
According to Mr Phumtham, the government has no intention of interfering in military affairs but aims to foster greater cooperation in working for the public interest.
With him at the Defence Ministry, Mr Phumtham said the armed forces would strongly fulfil their roles, actively help alleviate hardship for people and protect the constitutional monarchy.