A decision to this effect was taken at the party Executive Committee meeting here, a party statement said.
The appointment of Mohideen comes after the demise of former Union Minister and party National President E Ahamed on February one.
The National Executive Committee was presided by the party's Kerala State Unit President Syed Haider Ali and participated by former Kerala Industries Minister Kunhalikutty, MPs D Mohammed Basheer, Abdul Vahab, KAM Mohammed Abubacker and senior party leaders.
A two minute silence was observed in memory of Ahamed.
P V Abdul Wahab was elected as the Treasurer.