Basic dimensions (length, width and thickness), critical velocity of transporting seeds, sliding friction angle and the mass of pumpkin seeds, obtained from four fruit of various mass were determined. Based on the measurements, volume and thickness of each seed and its spherical index were calculated. Interdependence between the tested properties and indexes was evaluated based on the test for independent samples, analyses of variance, correlation and regression. It was found that the seeds mass is the most variable property and their length is the least variable. Empty and full pumpkin seeds should be separated with a pneumatic separator, where a vertical air stream of velocity approx. 5 m•s-1 is a separating element. Length and mass of seeds may be used at separation of seed material into quality fractions. As a result of separating the smallest seed fraction, a seed material may be obtained in which after the process of removing the fruit-seed coat, 95% of ripe seeds will be available.