The industrialization, agricultural activities, natural sources, and sewage treatment are main cause to release the harmful substances such as toxic heavy chemicals, organic and inorganic substance and volatile organic by-compounds in water bodies. Heavy metallic compounds are most serious toxic pollutants in potable water because they are not decomposable substances therefore accumulated in the cells. There accumulation with excess permissible level is harmful for living organism. Water is a unique universal aqueous medium has good capacity to dissolve the substance and because of this, it is highly vulnerable towards pollutes. These non-biodegradable heavy metallic compounds are easily dissolved in water and easily consumed by living organism through potable water. The heavy metal ions such as mercury (Hg), lead (Pb), zinc (Zn), cadmium (Cd), cobalt (Co) etc. are most frequently toxic chemical released from the industry into the water bodies. Where the consumption of cadmium compound is major concern, as it prolongs exposure causing raise of serious health issue such as kidney damage, cancer, or cardiovascular diseases. The selective and sensitive detection of the ion, even at low concentrations, is indispensable. This chapter is based on the latest trend of using porous nanomaterials in sensor fabrication, thin films of octadecylamine functionalized single-walled carbon nanotubes (ODACNTs) was deposited used using spin coating technique for sensing cadmium ion in aqueous medium. A thin film of ODACNTs offers not only strong adsorption properties towards cadmium ion but also provides an enormous gain in surface to volume ratio, and good mechanical and chemical stability also. The piezo and electrochemical responses were found to be linear in the given concentration range of cadmium ions. Interestingly, the piezo response modulates systematically and repeatedly from a maximum to minimum value due to voltage sweep onto working electrode during cyclic voltammetry indicating the interfacial phenomenon of adsorption and desorption of the ion onto the sensing surface.