Intermetallic compounds SrNi2Si and BaNi2Si were prepared by arc‐melting of stoichiometric mixture of the elements and subsequent annealing in welded niobium ampoules. Both compounds were investigated by X‐ray diffraction on powder as well as single crystal methods. The title compounds both crystallize in the BaNi2Ge structure type (space group Pmmn, Z = 2), a ternary ordered variant of TiCu3: a = 4.0296(9) Å, b = 6.5121(14) Å, c = 5.6839(21) Å, R1 = 0.040 for SrNi2Si and a = 4.0681(9) Å, b = 6.580(4) Å, c = 5.976(5) Å, R1 = 0.031 for BaNi2Si. The structure contains corrugated polyanionic [Ni2Si]2– layers, stacked according to the primitive sequence AA along the c axis. Six‐membered Ni rings adopt a boat conformation, silicon atoms are in the plane with nickel, and the alkaline earth cations sit between the layers. These two compounds extend the family AeNi2X (Ae = Ca, Sr, Ba; X = Si, Ge), where up to date CaNi2Si, SrNi2Ge, and BaNi2Ge are known. LMTO band structure calculations, including DOS, COHP, and ELF were performed to gain more insight into the electronic situation of SrNi2Si and BaNi2Si.