The water hyacinth (Eichhornia Crassipes) is native to South America, but has spread throughout the tropics. In some parts of the world it is a serious pest especially in Egypt. The plant has two or three shiny green squarish leaves, each with an air-filled bladder at the base, to which are attached roots. The bladder keeps the plant afloat. It grows at a prodigious rate, well able to clog lakes and waterways rapidly and leaves quickly covers the water surface. There for it's to be necessary of mechanical, chemical or any other means controls to allow for the extermination of water hyacinth but very few chemical compounds yielded promising results most of the chemical were rejected because of their ineffectiveness or obvious toxicity. The mechanical control is ineffective and very expensive because the vigorously vegetative sexually by budding and stolen production. There fore, the present work were carried out to control the water hyacinth from waterways in Egypt by thermal control. A laboratory studies were conducted to limit the optimum factors to put a design of controlling device for further work. A quick means of evaluating the pattern controlling of hyacinth was provided.  The effect of some factors, such as the average of bladder diameter (25; 30; and 35mm); resting time (four levels with intercept of one minute) and oven temperatures (200, 230,260 and 290⁰C) on controlling pattern,was investigated. The attained results indicated that the use of oven temperature (290^o) and resting time of 4 minutes at average bladder diameter of 25 mm gave the best controlling performance.