Automated Elementar Vario EL III CHNS analyzer was tested and evaluated by comparison with the classical methods for determination of total Carbon (C) and Nitrogen (N) in plant and soil samples. With proper standardization, calibration and sample preparation CHNS analyzer was shown to give reliable C and N analysis. The precision was demonstrated by recovery study done by adding different levels of C and N to plant and soil samples. It recovered 92 to 97% and 92 to 96% N and C to the tune of 97 to 99.1% and 98 to 99.4% from soil and plant samples, respectively. A simple linear regression analysis showed generally higher C and N values measured by CHNS analyzer with least variations (SD ±0.0001 to 0.0002) as compared to the classical Kjeldahl and Walkley and Black methods. The effect of sample weight and particle size on analysis by CHNS analyzer was also investigated which showed significantly higher C and N in particle size fraction of < 0.25 mm and with weight sizes of 5 and 10 mg for plant and soil samples, respectively. However, there was no effect of varying carbon and nitrogen content. In spite of being eco-friendly, reliable, less time consuming and low manpower requirement studies showed the high cost of analyzing samples (approx. Rs 90.93/US$ 2.02 per sample) with CHNS analyzer.