Here's why:

* Ionic Bonding: Barium oxide is an ionic compound, meaning it's formed by the electrostatic attraction between positively charged barium ions (Ba²⁺) and negatively charged oxide ions (O²⁻). These strong electrostatic forces require a lot of energy to break, leading to a high melting point.

* Lattice Structure: The ionic bonds in BaO form a tightly packed crystal lattice structure, contributing further to its high melting point.

Specifically, the melting point of barium oxide is around 1923°C (3493°F).