Waxy maize starch (APM), amylopectin wheat (APW) and amylopectin potato (APP) starches were subjected to high pressure treatment (650 MPa/9 min) in the excess of water. High sensitivity differential scanning microcalorimetry (HSDSC) and ¹H-NMR spectroscopy were used to analyse changes in the crystalline structure, gelling and osmotic properties of the pressurized starches. High pressure-treated APM and APW starches demonstrated almost complete gelatinisation of granules (GD=86% and GD=90%, respectively) and significant changes in their crystalline structure (melting of the A-type crystallites). Whereas, the degree of gelatinization of the “pressurised” APP starch accounted for 54%. The measurements of relaxation time constants (T₂) of water molecules in pressurized starch gels showed two different relaxations (46-720 ms and 8-120 ms). The complex relaxation of water molecules resulted directly from their different mobility that was triggered by differences in the structure of pressurized starch gels. These differences, i.e. ratio of swollen elements (granule remnants) to the non-swollen elements (crystalline, ordered structures), significantly affected not only the relaxation of water molecules in the gels but also determined their swelling index. The high pressure-treated starches after rehydration formed a gel structure that revealed low values of a swelling index.