In chemistry, a property is any aspect of a substance which is only seen by means of a chemical reaction. Simply speaking, chemical properties cannot be determined just by viewing or touching the substance. This is different from a physical property, which can be discovered without changing the substance's chemical structure.
Usually a chemical property is discovered by changing the substance's internal structure. When a substance goes under a chemical reaction, the properties will change drastically, resulting in chemical change. However, a catalytic property would also be a chemical property.
Chemical properties can be used for building chemical classifications. They can be used to identify an unknown substance or to separate or purify it from other substances.