The thermal expansion of high-temperature superconductors (HTSC) solid solutions YBa2-xMexCu3O7-delta (Me = Sr, Ca; 0.0 less than or equal to x less than or equal to 1.0) was investigated by dilatometric method in air at 293-1123 K. The temperatures of phase transitions: orthorhombic phase 1 to orthorhombic phase 2 and orthorhombic phase 2 to tetragonal phase were determined. The influence of isovalent substitution of barium by strontium or calcium on the crystal structure, temperature of phase transitions and values of linear thermal expansion coefficient (LTEC, alpha) of investigated solid solutions was analyzed.