Entered into force October 24, 1945.
In accordance with Article 110, the Charter entered into force on 24 October 1945, after ratification by the five permanent members of the Security Council and a majority of the other countries. Twenty-two countries subsequently deposited their instruments of ratification.
Czechoslovakia was an orginal signing member of the Charter. Signed June 26, 1946, deposited their notice of ratification October 19, 1945 and entered into force October 24, 1945. On January 19, 1993 both the Czech Republic and Slovakia deposited their declarations of acceptance to the Charter of the United Nations.
For a list of states that were admitted to the United Nations following the enter into force date of the the Charter see United Nations website.