Optical and scanning electron microscopic observations have been made of tin-iodide whiskers crystals grown by the gel-method. Most of the whiskers have been found to be of two types: (i) hollow and (ii) solid whiskers. The observations indicate that the formation of hollow whiskers is possible with or without the presence of impurities. By using electron micro probe, the overgrowth of tin-tetra iodide crystals on tin-iodide whisker crystals have been identified. A growth mechanism for tin-iodide whiskers have been suggested. The implications are discussed.