The printing ink industry is increasingly facing challenges in terms of high manufacturing costs and quality requirements. Rheological properties of the inks must be better understood for the development of production and application processes. Effects of pigment and dispersant content, varnish/solvent ratio, grinding medium, grinding time and storage period on rheological and printed optical properties were investigated for carbon black inks in this thesis work. The viscosity of the dispersant free ink was higher than inks with dispersant. The viscosity of the dispersant-free ink increased after three months storage whereas the viscosity of the dispersant-containing ink remained almost constant. Pigment content or V/S ratio increase resulted in higher viscosities. Grinding with 0.5 mm beads provided a finer size distribution and lower viscosities than ink ground with 0.8 mm beads. Longer grinding time increased the ink viscosities at pigment contents over 20 wt%. Thixotropy of dispersant free ink was determined to be about 12 times higher than 0.5 wt% dispersant containing ink. The thixotropy area of the 30 wt% pigment containing ink was determined to be five times higher than that of 25 wt% pigment containing ink. The thixotropy of the 25 wt% pigmented ink increased when the grinding time was changed from 30 to 60 minutes. Inks with coarser particle size distribution had higher thixotropy. Loss tangent (G’’/G’) at 10 Hz was used to create a correlation with color strength. Color strength of 14 out of 16 inks was determined higher with lower loss tangent values. Inks containing dispersant, higher pigment contents, varnish/solvent ratios close to one, increasing grinding time at higher pigment content increased the color strengths in printings.