A method of synthesizing cellulose nano-crystals from date palm seeds includes providing washed and dried date palm seeds, milling the date palm seeds to a fine powder, adding a bleaching agent to the fine powder to separate cellulose from the powder, placing the cellulose in a container with an acid solution to form a mixture, heating the mixture, isolating cellulose crystals from the mixture, and reducing the particle size of the cellulose crystals in the solution to provide cellulose nano-crystals. The particle size can be reduced by adding the cellulose crystals to a quantity of water to form a solution, and ultrasonicating the solution at about 90% amplitude for about 45 minutes to form cellulose nano-crystals. The cellulose nano-crystals can have a size ranging from about 5 nm to about 100 nm.