The supported and unsupported boehmite ($gamma$-AlOOH) membranes were prepared using a boehmite sol. The supported membrane was consisted of a porcelain support, two intermediate $alpha-{Al_2}{O_3}$ layers, and a top boehmite membrane. XRD patterns showed that the supported top membrane had a higher $ heta-$ to $alpha-{Al_2}{O_3}$ transformation temperature compared to the unsupported membrane. This result was also confirmed from microstructural study of the membrane. The shift in the phase transformation temperature should be explained by difference of a stress generated in the supported top membrane due to interaction between the support layers and the top membrane.