Department of Chemistry, Tripura University, Suryamaninagar-799 022, West Tripura, India E-mail : rndp09@gmail.com Manuscript received 06 May 2010, revised 29 December 2010, accepted 12 January 2011 Fluoride assisted stabilization of manganese(lll) has been demonstrated by synthesizing new mixed-ligand fluoromanganate(lll) complexes, A2[MnF4(L)] (A = K, L = citric acid, tartaric acid) from aqueous medium. Mixed-ligand fluoromanganate(lll) complexes have been synthesized from a reaction of KMnO4, 40% HF with corresponding ancillary ligands maintaining KMnO4 : HF : ancillary ligand ratio as 1 : 4 : 1 Newly synthesized complexes are stable in absence of moisture and are practically insoluble in common organic solvents. Complexes were characterized on the basis of elemental analyses, chemical determination of oxidation state, FTIR, electronic spectral studies, room temperature magnetic moment measurements and by thermal studies. The room temperature magnetic moment values for the complexes lie in the range 4.9 to 5.1 μB· Electronic spectral studies suggests an appreciable splitting of 5Eg ground state of manganese(lll) in the complexes leading to a distorted octahedral structure.