A new apparatus for measuring critical disolution time of 10 samples simultaneouslly, is described. The results are registered throught a printer. The factors that can influence on the precision of the results and their reproducibility and analysed, giving solutions for each case. An operating process for handling this new apparatus is described. It offers great opportunities in the measurements of critical disolution time techniques, for research, quality control of synthetic fibres production (production line and type of product), intermediate stages of production, finisher product, throwsters and textile testing laboratories.