The term dialdehyde starch is commonly used to describe the polyaldehyde material derived after periodate oxidative cleavage of the C2-C3 bond in starch. Upon oxidation of starch with periodate many inherent product characteristics are altered. The few things common between native potato starch and its dialdehyde form are the granular shape and the biopolymeric character. The newly introduced aldehydes strongly affect the inter and intramolecular interactions: helix formation becomes disrupted and crystallinity disappears. In particular, beyond a degree of oxidation of 40 %, dialdehyde starch granules were observed to be amorphous. Iodine staining and complexing with lysolecithine was also reduced pointing at a loss of helical shaped chains. The aldehydes in dialdehyde starch are not present as such, but appear to be hydrated or to be involved in hemiacetal or eventually acetal linkages with neighbouring alcohol functions. These hemiacetal bridges can be formed intra or intermolecular resulting in the formation of an intragranular network. The knowledge of fundamental physico-chemical properties is the bases to explain many aspects of the behaviour of dialdehyde starch during production and applications. In particular the swelling capacity in water has been subject of interest, both at room temperature and during gelatinization. Throughout this research dialdehyde starches with different degrees of oxidation have been studied to screen deviating product properties.