Pressmud and coir pith are bulk organic substrates useful for constituting soilless media. In the instrumental investigation, the lignocellulosic organic substances predominant in coir pith and pressmud were characterized in terms of proximate constituents, elemental composition and functional groups. The elemental composition studies by X-ray fluorescence spectroscopy (XRF) and proximate constituent analysis showed that both coir pith and pressmud contain sufficient amounts of macro-and micro-nutrients, as well as important organic constituents, such as sugar, cellulose, protein and wax. Scanning electron micrographs (SEM) revealed the fibrous and porous nature of both substrates. UVvisible and Fourier transform infrared spectroscopic analyses revealed the presence of lignin, hemicellulose and cellulose, and other characteristics of natural fibers. The cation and anion exchange reactions and the adsorption phenomenon exhibited by coir pith and pressmud were attributed to the functional groups on their surfaces. Hence, the findings support their suitability as a growing substrate for soilless crop production.