The synthesis of diethyl carbonate (DEC) from urea and ethanol was carried out over Mg–Zn–Al composite oxide catalysts derived from hydrotalcites (HTs). The catalytic results showed that the ternary hydrotalcites calcined at 450 °C with Mg:Zn:Al = 1:1.7:1 exhibited superior catalytic activity, and the highest DEC yield was 67.8%. Similar to ethanol, other alcohols such as methanol and butanol can also be transformed to corresponding dialkyl carbonates. Catalysts were characterized by XRD, BET, SEM and TPD with the aim of establishing a relationship between performance and structure. The results indicated that MgZn_1.7Al-450 with nanoplate morphology and more accessible active medium basic sites were favourable for obtaining much superior catalytic activity. Recycling experiments demonstrated that the catalyst could be successfully reused.