Gadancourt

{{Infobox French commune

|name = Gadancourt

|image = Gadancourt - Mairie 01.jpg

|caption = The town hall of Gadancourt

|image coat of arms = Blason Gadancourt 95.svg

|coordinates = {{coord|49.0969|1.8578|format=dms|display=inline,title}}

|arrondissement = Pontoise

|canton = Vauréal

|commune = Avernes

|elevation min m = 87

|elevation max m = 141

|area km2 = 4.68

|population = 83

|population date = 2015

|population footnotes = [https://www.insee.fr/fr/statistiques/fichier/3545833/Ensemble.pdf Téléchargement du fichier d'ensemble des populations légales en 2015], INSEE

|INSEE = 95259

|postal code = 95450

}}

Gadancourt ({{IPA|fr|ɡadɑ̃kuʁ|-|Fr-Paris--Gadancourt.ogg}}) is a former commune in the Val-d'Oise department in Île-de-France in northern France. On 1 January 2018, it was merged into the commune of Avernes.[https://www.legifrance.gouv.fr/eli/arrete/2017/9/25/INTB1726955A/jo/texte Arrêté préfectoral] 25 September 2017 {{in lang|fr}}