A material is made up of particles of an optionally-doped fluorosulphate. The fluorosulphate has a distorted Tavorite type structure of formula (A1−aA′a)x(Z1−bZ′b)z(SO4)sFf (I) where A=Li or Na, A′ 0 a hole or at least one doping element, Z=at least one element selected from Fe, Co and Ni, Z′=a hole or at least one doping element, the indices a, b, x, z, s, and f are selected to assure the electroneutrality of the compound and a≧0, b≧0, x≧0, z>0, s>0, f>0, the respective quantities a and b of dopant A and Z′ being such that the Tavorite type structure is preserved. The material is obtained from the precursors thereof by an ionothermal route or ceramic route in a closed reactor. The material is of particular use as an active electrode material.