General Prayuth Chan-ocha, in an address to senior military officials, announced the date as part of a three-phase plan of reconciliation, formation of a government and elections to be rolled out by the ruling National Council for Peace and Order.
He told a meeting about the 2015 budget. "A government will be set up by August, or at the very latest September."
He did not say whether the government would be comprised of civilian or military figures.
The army took power on May 22 in a bloodless coup after six months of sometimes violent street protests pitting mainly rural supporters of ousted Prime Minister Yingluck Shinawatra against her Bangkok-based, royalist opponents.
Gen. Prayuth repeated in his address that a temporary constitution would be drafted within three months.