n-Alkyl modified silica gels are widely used and popular chromatographic column materials for molecular seperation, owing to their versatility and high thermal stability. These systems constitute of chemically immobilized n-alkylsilanes where, in general, the length of alkyl chain varies from C₈ to C₃₀. The degree of branching and cross-linking (i.e. the surface coverage density) for the phase varies with the reaction conditions employed during the modification process. The surface coverage density as well as the length of the n-alkyl chain influence dynamical and conformational features of these phases which in turn play an important role in shape selectivity, molecular recognition and discrimination. Our studies focus mainly on understanding of these aforementioned aspects (i.e. the dynamics and chain order) for which we utilize solid-state dynamic ²H NMR (supported by ¹³C and ¹H MAS NMR investigations) and FT IR techniques. With the help of ²H NMR investigations (via lineshape and relaxation experiments) on selectively deuterated samples the dynamics of the alkyl chain, between 150 K and 360 K, is examined. The subsequent analysis of the experimental data is done by employing suitable simulation programs which provide the desired molecular parameters, such as rate constants of various chain motions, etc. FT IR studies, on the other hand, are used to determine the localized as well as the overall conformational disorder present in the systems which, as mentioned before, affect the shape recognition and selectivity properties of the n-alkyl modified interphases. The studies are further addressed to the evaluation of the influence of various solvents on the mobility and conformational disorder of the n-alkyl chains bound to the silica surface.