The research was conducted to understand the effect of zeolite on the effectivity of water hyacinth compost and to determine the best doses of zeolite on water hyacinth compost to improve the growth and production of red chili in coastal sandy soil of South Yogyakarta. The study was carried out from January through July 2016 at the greenhouse and experimental farm of Faculty of Agriculture, Universitas Muhammadiyah Yogyakarta. This research was designed using Completely Randomized Design (CRD), consisted of four treatments i.e 4 tons/hectare of water hyacinth compost (K0), 4 tons/hectare of water hyacinth compost + Zeolite at dose of 6 % of the water hyacinth compost doses (K1), 4 tons/hectare water hyacinth compost + Zeolite at dose of 8 % of the water hyacinth compost doses (K2), and 4 tons/hectare water hyacinth compost + Zeolite at dose 10 % of the water hyacinth compost doses (K3). The results showed that zeolite could improve the effectivity of water hyacinth compost in the coastal sandy soil of South Yogyakarta and significantly increased the plant height, leaf number, fresh and dry weight of plants, fresh and dry weight of roots, and fresh weight of red chili fruits. Moreover, red chili planted on Zeolite with doses 8.84 % of the water hyacinth compost can produce 2.77 tons/hectare of red chili fruits.