The 67-year-old is believed to be on the verge of sealing a cut-price £14m deal for the London club, who are currently 19th in the Championship.
Duchatelet's approach comes after a proposed purchase by American Josh Harris, who owns the Philadelphia 76ers NBA side and New Jersey Devils NHL team, collapsed last month.
In a statement on Charlton's website, chairman Michael Slater said: "Very constructive discussions are ongoing (with Duchatelet) which we hope to conclude soon."
Duchatelet is a former Belgian senator who made his millions in the electronics industry.
He already owns Standard Liege, who he took over in 2011 and are presently four points clear at the top of the Belgian Pro League.
Charlton face Sheffield Wednesday on Sunday, having won just one of their last six league matches - a run that has left them four points above the relegation zone.