In order to study the effect caused by atomic substitution on the phase transition in Pb(Yb1/2Nb1/2)O3, crystallographic and dielectric properties of (Pb1-xBax)(Yb1/2Nb1/2)O3 ceramics system have been investigated for 0 less-than-or-equal-to x less-than-or-equal-to 0.5, as a function of temperature. A continuous series of solid solutions with ordered perovskite structure has been found. While the antiferroelectric transition temperature markedly decreases with increasing Ba concentration, the value of dielectric constant in the immediate vicinity of the peak is maximum at x=0.14. It has been revealed that the low symmetry phase changes from the antiferroelectric state to ferroelectric one near x=0.12. The antiferroelectric-paraelectric transition is relatively sharp for 0 less-than-or-equal-to x less-than-or-equal-to 0.1, but the ferroelectric-paraelectric transition is diffuse. A brief discussion of the effect caused by Ba substitution is given.