An irreducible version of free massless spin-5/2 gauge fields is analyzed from the point of view of the Lagrangian Sp(3) BRST method. The irreducible formulation is obtained by means of introducing one purely gauge supplementary Majorana spinor. An appropriate gauge-fixing procedure is developed, such as to benefit from a direct link with the standard antifield-BRST method. The comparison with related results from the literature is discussed.

PACS numbers: 11.10.Ef