McLeod joined Charlton last summer from MK Dons for a fee of £1.1 million, but has struggled and has only scored one goal in 18 first-team appearances.
He now joins former Addick Kevin Lisbie at Layer Road, and could make his debut for the relegation threatened club today, against Wolves.
Meanwhile, Charlton boss Alan Pardew has signed midfielder Dorian Smith from non-league side Tooting and Mitcham.
Smith had been on trial with the Addicks and played in Wednesday night's 3-1 reserve victory over Southampton.
He now joins former Addick Kevin Lisbie at Layer Road, and could make his debut for the relegation threatened club today, against Wolves.
Meanwhile, Charlton boss Alan Pardew has signed midfielder Dorian Smith from non-league side Tooting and Mitcham.
Smith had been on trial with the Addicks and played in Wednesday night's 3-1 reserve victory over Southampton.