A magnesium sulfite pulp producer modified its pulping process to dissolving pulping in 2011 and needed a purification stage after the digester to obtain a sufficiently low hemicellulose content. The dissolving pulp was intended for viscose production and an R-18 value of at least 95% and an intrinsic viscosity below 550 dm(3)/kg was requested. The results showed, as could be expected, a correlation between lower dissolving pulp yield and a higher degree Of purification with respect to cellulose. The R-18 values and the intrinsic viscosities of the dissolving pulps were found to increase with increasing sodium hydroxide concentration and/or higher temperature in the extraction Stage. The pulp yield was found to be higher with higher temperature for the cold caustic extraction stage (CCE); for hot caustic extraction (HQ E) the pulp yield became lower with higher temperature. The specified R-18 value was easiest to reach using hot caustic extraction.