Excessive use of chemical fertilizers typically leads to solution nutrient concentration higher than optimal for the plant and results in a potential for leaching losses or precipitation of nutrients. One of the effective methods to overcome this problem is the development of slow-release fertilizers. Biopolymers are the most suitable compounds for synthesis of the slow-release systems of nutrients. In this study, alginate with and without combination with zeolite clay in zeolite:alginate ratios of 1:4 and 1:8 were used to produce slow-release systems of zinc (Zn) and copper (Cu). To load the systems with Zn or Cu, the synthesized systems were put in solutions of zinc sulfate and copper sulfate with concentration of 300 and 200 mg l -1 , respectively. For the release experiments, specified amounts of loaded matrixes in two forms (dried or moist) were transferred into vessels containing 0.01 M CaCl 2 solutions and the amounts of released Zn or Cu were measured from 24 hours to 58 days. Results showed that releases of Zn and Cu from the moist systems were greater than those form the dried ones. Release of Cu from the moist systems continued for 58 days, while, release of Zn lasted for 17 days. Releasing time of Zn from the dried systems, however, was considerably longer than that from the moist systems. Time-dependent Cu and Zn release data was sufficiently explained by pseudo-first order, power function and parabolic diffusion kinetic models. Pure alginate systems showed the greatest amounts of releasable Cu and Zn as estimated by the pseudo-first order model. Moreover, rate of Zn and Cu release from pure alginate system was greater than those of the zeolite:alginate systems showing the role of zeolite clay in decreasing the release of nutrients from alginate. Diffusion rate constants (k i ) derived from parabolic diffusion models were also higher for pure alginate as compared to zeolite:alginate systems. Overall, alginate and zeoite:alginate hybrids can be applied as an environment-friendly products for synthesis of slow-release systems of Zn and Cu. Key words : Alginate, Biopolymer, Zeolite, Kinetics, Micronutrients, Slow-release.