Thailand and Cambodia have agreed to jointly set up a team to survey the watershed at the Chong An Ma pass in Ubon Ratchathani province so a clear boundary can be drawn.
The decision was made on Saturday following months of occasional face-offs over the 600-metre border line.
Once the watershed is determined, the boundary will be clear and a permanent pass will open for bilateral trade.
The army's survey department will lead the Thai side in the team while civilians from Prime Minister Hun Sen's Office represent Cambodia, said Col Natt Sri-in, chief of staff of the Suranaree Force.
The team will look for the watershed, to be used in determining the boundary, within 90 days.
The disputed part is the 30m distance where Cambodia excavated to build a road. Thailand protested against the move in late 2014, claiming it destroyed the watershed when the boundary had yet to be drawn.
After the boundary is clear, the two sides will build roads to convene at the watershed to further promote bilateral trade. At present, Chong An Ma is one of the 18 passes along the Thai-Cambodia border but with a temporary status.