Swelling and non-swelling properties of bentonite particles play an important role in their performance as well as their applications. Swelling bentonites, containing montmorillonite as the main constituent, are mainly used in drilling fluids, bonding sands in foundry molds, iron ore palletizing, and environmental sealing, while non-swelling ones are primarily used as adsorbents in bleaching earth and heavy metal removal. Experimental studies on 10 natural bentonite samples, namely S1 to S10, were conducted to identify the swelling behavior of the samples. XRD studies showed the presence of nanoporous and nanostructured montmorillonite species along with some other clay and non-clay mineral impurities. XRF studies through the measurement of CaO and Na2O weight percents provided a good measure to determine swelling or non-swelling properties of bentonites. XRD and XRF analyses demonstrated that Na2O in samples S5 to S8 belongs to montmorillonite, which is a clay mineral. The first main peak of montmorillonite in its XRD pattern was another guide in assigning the type of the bentonites. BET surface area measurement was employed to verify the former observations. A higher surface area was measured for swelling bentonites, while the highest surface area of 78m2/g was obtained for the swelling S8 bentonite. The studies showed that samples S9 and S10 are non-swelling, samples S4, S7, and S8 are swelling, samples S2, S5, and S6 are swelling/non-swelling, and sample S3 is a non-swelling/swelling bentonite.