The K₂NiF₄ type diluted solution YCa(Al_1-xCr_x)O₄ (0 ≤ x ≤ 0.10) is studied with respect to both crystal chemistry and magnetic properties, mainly in order to obtain some evidence of Cr³⁺ segregation phenomena in the octahedral layers. The Al³⁺ → Cr³⁺ replacement results in a strong anisotropic variation of the cell constants in terms of an increase and a decrease in the a and c parameters, respectively, of the tetragonal cell. Such behaviour is largely dependent on the M-O_apical distances in the (Al,Cr)-O₆ octahedra, as well as in the (Y,Ca)-O₉ polyhedra, which show a coupling of their variation. On the basis of the temperature (80, 400 K) and Cr³⁺ concentration dependence of the magnetic susceptibility, which is used in the Heisenberg-Dirac-Van Vleck approach for modeling the magnetic exchange interactions, a significant deviation of the Cr³⁺ distribution is found with respect to a statistical distribution. The amount of Cr³⁺ clusters is lower than in the perovskite solid solution YAl_1-xCr_xO₃, owing to the lower dimensionality of the K₂NiF₄ type structure of the YCaAl_1-xCr_xO₄ series. The 2D character of the exchange interactions is found to be stronger than in pure chromite, YCaCrO₄.