Zeolite Cs-ABW nanocatalyst has been hydrothermally synthesized without using any harmful organic template. The zeolite nanocrystal with very high solid yield (81.88%) can be obtained within 60 min and at 180 $^{\circ}$C (∼ 20 atm), conditions that are much faster and gentler than the existing synthesis methods. The orthorhombic Cs-ABW nanocrystals (mean size of 32 nm) have high aluminum content (Si/Al ratio $=$ 1.14) and possess high basicity. The nanocrystals also exhibit better catalytic activity than conventional homogeneous catalysts in the Henry (nitroaldol) reaction of benzaldehyde with nitroethane under microwave heating conditions. The nanocatalyst does not suffer from coking and leaching problems. It can be reused without loss of reactivity even after five consecutive runs under the described reaction conditions.