A sealed-tube type 14 MeV neutron generator with maximum neutron output of 1011 n/sec, incorporating a pneumatic sample transfer system of single-tube type and with a single rotation of the sample during neutron irradiation, is used to develop a method for determining oxygen content in steel in the ppm range with the best precision, and at the same time, to make the process suitable for routine work in industrial applications. The pneumatic sample transfer system is made to incline at an angle of about 20° towards the horizontal at the irradiation station. Together with a constant pressure gas reservoir for providing a constant optimum gas pressure in the transfer tube, the system gives a result of nearly perfect reproducibility in the operation. A pulse shape analyser system incorporating an organic scintillation detector is used for monitoring neutron flux level during the neutron irradiation of the sample. The percentage standard deviation of the neutron counts by the present monitoring system ranges from 0.9 to 2.7% with 0.5% as the percentage statistical deviation alone. Polyethylene, of oxygen content 163 ppm determined by comparison with lucite, is used as the steel sample carrier. A 3 × 3 in. NaI(Tl) crystal is used with a single channel analyser to count the 6.1 and 7.1 MeV gamma rays emitted from 16N as a result of the reaction 16O(n, p)16N. An optimum combination for the time of irradiation, delay and counting of the induced activity; of 30, 0.1 and 30 sec, respectively, is chosen in the present experiment. Thus, for a 100 g steel sample with an oxygen concentration of 170 ppm, the percentage standard deviation is about 4.4% which is, in fact, the counting statistic itself, resulting from a neutron flux level of 1.3 × 108 n/sec cm2 at the sample. As the present activation analysis makes use of the comparison method, a steel-mylar standard made of layered steel and mylar discs is prepared and a calibration curve constructed. A method of correcting the oxygen contribution in the polyethylene sample carrier is devised and the content of oxygen in the steel standard is determined. A survey of neutron flux distribution is also attempted and it is found that nearly symmetrical distribution of the flux, about the centre of the sample carrier which is placed with its axis in parallel to the plane of the disc-shaped target of the neutron-generating tube, is far from being flat.