This study describes the technique and procedures used for the simultaneous determination of elements involved in Instrumental Neutron Activation Analysis, applied to some geological samples as a sensitive and non-destructive tool. Using Isotopic Neutron Source, the delayed gamma-rays emitted due to neutron capture have been applied for the investigation of the elemental constituents and concentrations of major, minor and trace elements in such samples. The experimental investigations were carried out at the scale of researcher's practices at the chosen site by measuring soil/rock nutrient contents from hydrologically isolated farmland/site plots. Using detailed sampling procedures with special precautions, against contaminations, to yield meaningful results, soil/rock samples have been collected from selected areas of East Gojjam, pulverized, homogenized and prepared for irradiation. The samples were properly prepared together with known standards of potassium iodide or cupric sulphate or arsenic trioxide (one /or both at a time), and simultaneously irradiated in to isotopic neutron ux in the same irradiation position. After activation, the samples were subjected to gamma-ray spectrometry, using a high-purity germanium detection system and computerized multichannel analyzer. The gamma-ray spectra from the irradiated samples were measured by high resolution gamma-ray spectrometry with a calibrated germanium detector. Both qualitative and quantitative approach to data collection and analysis were used in order to gain insight into what should be acceptable to the community. The results obtained have a practical interest in view of possible applications to the technology of extraction and exploration of a variety of industrial, metallic, cement minerals, and geothermal energy and coal deposits. These results tend to agree with the lowest values reported in the literature, and the analytical precision is su cient for the determination of the standard deviation of the distribution of all elements in East Gojjam and these results were brie y discussed within the text of this research work. In carrying out the analysis, the best and most convenient method being the Instrumental and /non-destructive Neutron Activation Analysis was adopted, and NAA has matured and attained analytical competence providing not only rapid, quantitative, qualitative, simultaneous, multi􀀀element analysis but also crucial validation support to programmes using di erent analytical techniques. This method of analysis is generally multi-element and experimental conditions can be designed to be non􀀀destructive to the sample, and it plays a leading role among analytical techniques in the eld of environmental research related to human, animal and plant health. Studies of di erent radionuclide and trace elements in the environmental samples are very important for health physics, research and education. Many forms of elements are possible in environmental samples which may be hazardous for human being, animals and also plants. Most of them have the potential for both benefcial and harmful effects / Environmental Sciences / D. Phil. (Environmental Science)