Hydrogen bond is electrostatic in nature. The strength of hydrogen bond is generally 20-40 KJ mole-1; while that of ordinary chemical bond is between 200-400 KJ mole-1. But it has important effects on the physical properties of the compounds.
For example the compounds with hydrogen bond have higher melting and boiling points than related compounds, but without hydrogen bond. Although covalent compounds are generally insoluble in water, those with hydrogen bond are soluble in water. The compounds with hydrogen bond have also higher viscosity.