[en] The '114' YBaCo₄O₇ cobaltite undergoes structural transition just beyond room temperature at T_S∼310 K. Correspondingly, its signature in the physical properties is detected by T-dependent measurements of electrical resistivity, magnetic susceptibility and thermoelectric power. It is found that low-level substitutions of divalent (M=Zn²⁺) or trivalent (M=Ga³⁺, Al³⁺) cations for cobalt according to the YBaCo_4-xM_xO₇ formula with x≤0.4 have a strong impact upon this transition. On the one hand, Zn²⁺ substitutions preserve the transition but with T_S decreasing as x increases. On the other hand, for x=0.2 Ga³⁺ or Al³⁺, the transition is suppressed, i.e., for only 5% trivalent foreign cation substituted for cobalt. Though at first, this contrasted behaviour between divalent and trivalent substituting cations appears to be linked to the opposite evolution of hole carriers 'Co³⁺' concentration with x, a possible destabilization of 3Co²⁺: 1Co³⁺ charge ordering induced by the M³⁺ cations is considered. - Graphical abstract: The temperature characteristic of the structural transition in YBaCo₄O₇, indicated by an abrupt jump of the Seebeck coefficient, decreases as Zn²⁺ is substituted for cobalt. In contrast, Al³⁺ or Ga³⁺ substitutions suppress this structural transition