Doleans, M. Afanador, R. Ball, J.A. Barnhart, D.L. Blokland, W. Crofford, M.T. DeGraff, B. Hannah, B.S. Howell, M.P. Kim, S.-H. Lee, S.W. Mammosser, J.D. McMahan, C.J. Neustadt, T.S. Saunders, J. Stewart, S.E. Strong, W.H. Tyagi, P.V. Vandygriff, D.M. JACoW Geneva, Switzerland A new In-situ plasma processing technique is being developed at the SNS (Spallation Neutron Source) to improve the performance of the cavities in operation. The technique utilizes a reactive low-density room-temperature plasma to remove top-surface hydrocarbons. This increases the work function of the cavity surface and reduces the overall amount of electron activity; In particular it increases the field-emission onset, which enables to operate a cavity at higher accelerating gradient. Development of the basic plasma processing parameters and effect on the Niobium surface can be found elsewhere *,**. Details on the results for in-situ plasma processing of dressed cavities in the SNS HTA (horizontal test apparatus) will be reported here.