Finding new economic means of upgrading residuals is becoming increasingly important. In this work, the upgrading of Arabian Light vacuum residue under asphaltene stability limit by steam catalytic cracking using unsupported ultra-dispersed (UD) alkali and a non-noble transition metals catalyst is investigated in a continuous open tubular reactor pilot plant. The experiments are conducted with K/Ni UD catalyst under 260 psig at process temperatures of 430-445 degrees C and LHSV of 5-10.5 h(-1). Experimental results showed a relative increase in the residual oil conversion of 13% by Aquaprocessing at the minimum asphaltene stability limit when compared to conventional thermal cracking. With the use of O-18 labeled water, it is confirmed that the UD catalyst during reaction is capable of dissociating water into hydrogen and oxygen radicals at near visbreaking conditions.