Suspensions of carbonyl iron powder in oil (CIP/O) have a very promising application on controlled fluids processes, as a very high local viscosity can be produced in the region in which the magnetic field is applied, allowing some control of the flow. In experiments performed in tube viscometers the flow can be completely stopped in some circumstances, such as specific pressure, magnetic field strength and particles concentration. This work presents our initial results of the jet morphology produced at the tip of the tube of a CIP/O, in terms of the applied pressure or of the applied magnetic field. A 3-CCD camera positioned in front of the jet collected "frozen" pictures of the jets produced in different conditions. Morphologic parameters of the jet such as the angle of the cone and the amplitude of the jet oscillation can be measured. Thus, the effect of the magnetic field on the fluid can be visualized and parameterized. It was observed that the perturbation due to the application of the magnetic field on the tip of the tube causes large changes on the jet oscillation. The amplitudes of the oscillations are very sensitive to the parameters described above. © World Scientific Publishing Company.197-912701275Harrison, G.H., Mun, R., Cooper, G., Boger, D.V., (1999) J. Non-Newtonian Fluid Mech., 85, pp. 93-104Sabadini, E., Figueredo, R.C.R., Optical Density in the study of Fragmentation of Dilute Polymer solutions Jets (2000) 9th International Symposium on Flow Visualization, , EdinburgDang, A., Ooi, L., Fales, J., Stroeve, P., Yield stress measurements of magnetorheological fluids in tubes (2000) Ind. Eng. Chemistry Res., 39 (7), pp. 2269-2274Sudo, S., Funaoka, M., Nishiyama, H., Impact of droplets of magneto-rheological suspension under applied magnetic fields (2002) J. Intell. Mat. Syst. & Structures, 13 (7-8), pp. 409-413Sabadini, E., Alkschbirs, M.I., (2004) Journal of Physical Chemistry - B, 108, pp. 1183-1188