Method for producing a porous nuclear fuel including uranium, optionally plutonium, and optionally at least one minor actinide which includes the following series of steps: a) a step of compacting a mixture including a first type of agglomerate including uranium oxide in the form of uranium dioxide UO 2, optionally plutonium oxide, and optionally at least one minor actinide oxide, and a second type of agglomerate including uranium oxide in the form of triuranium octaoxide U 3 O 8, optionally plutonium oxide, and optionally at least one minor actinide oxide; b) a step of reducing the compacted mixture in a reducing medium, so as to reduce all or part of the triuranium octaoxide U 3 O 8 into uranium dioxide UO 2, in which the agglomerates of the second type are prepared prior to the compacting step by the following series of operations: i)an operation of preparing a charge solution comprising a nitric solution including uranium in the form of a complex of hydroxylated uranyl nitrate and optionally plutonium and/or at least one minor actinide in the form of plutonium nitrate and/or nitrate of at least one minor actinide; ii) an operation of passing said solution through a cation exchange resin comprising carboxylic groups, said resin being constituted of beads of cation exchange resin comprising carboxylic groups, such that the uranium in uranyl form and optionally plutonium and/or at least one minor actinide in cationic form remain fixed to the resin; iii) an operation of heat treatment of said resin in a medium comprising oxygen, thereby obtaining the agglomerates of the second type. a) a step of compacting a mixture including a first type of agglomerate including uranium oxide in the form of uranium dioxide UO 2, optionally plutonium oxide, and optionally at least one minor actinide oxide, and a second type of agglomerate including uranium oxide in the form of triuranium octaoxide U 3 O 8, optionally plutonium oxide, and optionally at least one minor actinide oxide; b) a step of reducing the compacted mixture in a reducing medium, so as to reduce all or part of the triuranium octaoxide U 3 O 8 into uranium dioxide UO 2, in which the agglomerates of the second type are prepared prior to the compacting step by the following series of operations: i)an operation of preparing a charge solution comprising a nitric solution including uranium in the form of a complex of hydroxylated uranyl nitrate and optionally plutonium and/or at least one minor actinide in the form of plutonium nitrate and/or nitrate of at least one minor actinide; ii) an operation of passing said solution through a cation exchange resin comprising carboxylic groups, said resin being constituted of beads of cation exchange resin comprising carboxylic groups, such that the uranium in uranyl form and optionally plutonium and/or at least one minor actinide in cationic form remain fixed to the resin; iii) an operation of heat treatment of said resin in a medium comprising oxygen, thereby obtaining the agglomerates of the second type. i)an operation of preparing a charge solution comprising a nitric solution including uranium in the form of a complex of hydroxylated uranyl nitrate and optionally plutonium and/or at least one minor actinide in the form of plutonium nitrate and/or nitrate of at least one minor actinide; ii) an operation of passing said solution through a cation exchange resin comprising carboxylic groups, said resin being constituted of beads of cation exchange resin comprising carboxylic groups, such that the uranium in uranyl form and optionally plutonium and/or at least one minor actinide in cationic form remain fixed to the resin; iii) an operation of heat treatment of said resin in a medium comprising oxygen, thereby obtaining the agglomerates of the second type.