Abstract: The non-destructive method is for measurement of recycled pulp or pulp immersed in suspension that enables real-time or on-line evaluation of particles in recycled pulp or pulp, especially for evaluation of particles including inks contained in recycled or de-inked pulp for their characteristics related to sizes, shapes, areas, amount, concentration, absorption coefficients, spectral characteristics such as color locus (L*, a*, b* values) and parameters, which are equivalent to an effective residual ink content (ERIC) or the ink elimination (IE) or detachment (ID), but independent of the size distribution of inks. The method can additionally be used for real-time or on-line recognizing inks from the other particles and distinguishing inks, which are already detached from or still attached to fibers and identification of the pulp fibers and fiber-based particles in recycled pulp or pulp from the non-fiber particles.