Experimental investigations of crystallization in a family of uranyl triacetate compounds with Na, K, Rb and Cs were performed. The crystal structures of two novel Cs- and Rb-bearing tri(acetato)uranylates were solved, and the content of H ₂O molecules in the crystal structure of K-bearing uranyl triacetate was refined. Synthesized compounds were analyzed using IR spectroscopy and single-crystal X-ray diffraction. Crystal chemical analysis of the M[(UO ₂)(CH ₃COO) ₃](H ₂O) _n family (M = Na, K, Rb, Cs; n = 0-1.0) reveals the sequence of structural transformations depending on the size of alkali cation resulting in the symmetry reduction from cubic P?2 ₁3 (for Na), through tetragonal I?4 ₁/a (for K and Rb) to triclinic P?1 space groups (for Cs), which is in accordance with the principle of morphotropism, suggested by Paul von Groth, founder of the Zeitschrift für Krystallographie journal, in 1870.