This study was conducted to investigate some engineering properties of Cercis siliquastrum L. seed namely, geometrical properties (length, width, thickness, geometric mean diameter, sphericity, surface area, seed volume), gravimetrical properties (thousand seed mass, bulk and true densities, porosity), and mechanical properties (fracture force, absorbed energy, toughness, power requirement and firmness) for different acid treatment and stratification durations. All properties of C. siliquastrum L. seed were evaluated as a function of acid (H2SO4) treatment durations (0-15-30-45-60-120 min) and to the 0-1-2 months stratification. The duration of seeds in acid has eroded the coat of the seed and the axial dimensions of the seed which are not scarified are decreased. Since the stratification duration of seed in humid perlite increases the ability of water absorption tapered coat, axial dimensions have increased contrarily. As the surface area and volume of the seed decrease in those that were not scarified in axial dimensions, it has increased importantly in the first and second scarification months. The opposite is determined in sphericity. According to the different stratification durations of seeds which are not applied with acid treatment, minor changes are determined in seed mass, bulk and true densities and porosity values. In acid treatments of 15-120 min significant changes are recorded apart from true density between stratification durations. Fracture forces according to unstratification, first and second months of scarification of seeds have decreased from 359.3 to 293.8 N, from 315.9 to 64.2 N, from 226.8 to 45.5 N respectively. The differences according to acid treatment and stratification duration of measured fracture forces and absorbed energy, toughness and firmness values are found statistically important.