Polymer-free colorant dispersions, based on yellow and red azo pigments as well as copper phthalocyanine, cocrystallized or mixed with ionic synergists, enable high pigment loadings and formulation flexibility in inkjet inks. Careful selection of synergist structure allows to significantly improve dispersion stability towards various ink cosolvents and surfactants. Structural factors, responsible for synergist performance depend on the substitution pattern in both azo pigment and synergist. It was shown that for optimal affinity to the pigment surface and for the stability of the final dispersion the synergist structure does not have to exactly match the structure of parent pigment. The yellow dispersions are obtained from two most common organic pigments, based on Acetoacetanilide chemistry – Pigment Yellow 1 and Pigment Yellow 74. For both of these colorants the dispersions with up to 30% solid contents and very low viscosity were prepared. Crystal structure differences between PY1 and PY74 dictates the synergist choice and explains variations in stability. Magenta (Red) dispersions were obtained from Pigment Red 8, Pigment Red 23, Pigment Red 269 and a few others, all based on Naphtol AS chemistry. These pigments provide an alternative for quinacridones, traditionally used as M component of digital CMY triade. Although their color is generally less bluish, than that of quinacridone, Naphthol AS pigments are a lot stronger and certainly less expensive, than quinacridones. It was also possible to generate cyan dispersions, based on PB15, using modified copper phthalocyanines as synergists.The technology of dispersion with synergists can be designed as a simple mixing process, without using additional chemicals. The process generates minimal amount of effluents, most of which can be recycled. All dispersions demonstrate good stability of particle size in presence of surfactants and cosolvents/humectants even at high loadings.