In the reaction between calcium oxide (CaO) and carbon dioxide (CO₂), the products can be formed by their combination. The chemical equation for the reaction can be represented as follows:
\[ \text{CaO} + \text{CO}_2 \rightarrow \text{CaCO}_3 \]
The product of the reaction is calcium carbonate, which has the chemical formula \( \text{CaCO}_3 \).
In summary, the product of the reaction between calcium oxide and carbon dioxide is calcium carbonate (\( \text{CaCO}_3 \)).