The KOD and its founder, Mateusz Kijowski, shot to prominence in 2016 during a string of protests.
The KOD and its founder, Mateusz Kijowski, shot to prominence in 2016 during a string of protests against Poland's rightwing populist government for alleged rule-of-law violations.
But the movement lost steam this year after allegations surfaced in January that Kijowski, a 48-year-old IT specialist and blogger, may have misappropriated funds raised during the protests.
Prosecutors allege that Kijowski used his IT company in 2016 to bill the KOD for 28,000 euros' worth ($31,900) of services it never provided.
The KOD treasurer, identified under Polish law as only Piotr C., faces identical charges, prosecutors said.
The two men risk up to eight years in prison if found guilty.
Kijowski has apologised to KOD supporters for having put the movement "in a crisis situation".
"I have opened up the opportunity for attacks on the KOD, exposing thousands of activists and supporters. I ask you all for forgiveness," he said in a Facebook post when the allegations of financial misconduct surfaced in January.
Kijowski stepped down as KOD leader this year and was replaced in May by communist-era dissident Krzysztof Lozinski, an author and mountain climber.
The KOD sprang to life in late 2015 when tens of thousands of people descended into the streets to protest alleged political interference with the Constitutional Tribunal by the freshly elected Law and Justice (PiS) government.
Since winning power in October 2015, the populist PiS administration has pushed through a string of changes that critics say undermine the independence of public broadcasters and the judiciary, including the Constitutional Tribunal.
The EU agreed in May to continue holding talks with Warsaw aimed at ending the alleged rule-of-law breaches, backing away from threats of sanctions.