The optical limiting properties of alloyed Cd0.5Zn0.5S quantum dots associated with erythrosine dye are analyzed using 532 nm, 40 ps pulses. We show that joint influence of saturable absorption, reverse saturable absorption and two-photon absorption cause the optical limiting of 532 nm radiation at the pulse energies exceeding 1 mJ. The nonlinear refraction and nonlinear absorption of these quantum dots associated with different organic dyes were studied using 1064 nm and 532 nm radiation. The nonlinear refraction index and nonlinear absorption coefficient of Cd0.5Zn0.5S quantum dots were measured at λ = 1064 nm to be 2 × 10-13 cm2 W-1 and 1.2 × 10-8 cm W-1, while the reverse saturable absorption of Cd0.5Zn0.5S quantum dots and erythrosine at λ = 532 nm was almost two orders larger. The potential applications of these quantum dots for high-order harmonic generation are discussed.