Deformation behavior and formability limits of thixo-molded Mg AZ61L alloy and regular Mg AZ61 alloy sheets (with similar chemical compositions except for Mn content) were experimentally investigated at elevated temperature. Tensile (uniaxial), hydraulic bulge (biaxial) tests as well as closed-die hydroforming tests were conducted to understand the material behavior at temperatures ranging from 25 degrees C to 300 degrees C and strain rates at 0.0013, 0.013 and 0.13 s(-1). It was found that flow stress and the maximum plastic strain increased with increasing temperature and decreasing strain rate. Closed-die warm hydroforming tests were also performed to determine the process window for the sheet alloy. Die cavity filling ratios and thinning of the sheet blanks were measured with non-contact optical photogrammetry. Results indicated that lower strain rates and higher temperatures increase formability, particularly above temperatures of 200 degrees C.