Dynamical Evolution of Selected Galactic Open Star Clusters In this doctoral thesis, probable cluster members of 40 open clusters with Age ≥ 100 Myr have been selected by means of statistical field star decontamination applied to 2MASS JHKs photometric data. By fitting Padova isochrones to (J-H) - J diagrams, the interstellar reddening E(J-H), and consequently, E(B-V), the apparent distance modulus (m-M)v, the distance (d), and the age (A) of these clusters have been inferred simultaneously. Structural parameters have been derived by fitting theoretical King profiles to the observed stellar radial density profiles.