Abstract: A glass fibre reinforced plastic substrate provides the mechanical strength and thermal properties for use e.g. in flat display devices. There is a trend towards flat display devices comprising flexible displays. Such display devices also need flexible substrates, and a method to produce such flexible substrates cost effectively. To make such flexible display by conventional manufacturing technologies that have been applied to produce the LCD displays, glass substrates need to be replaced with elastic substrate materials that are deformable even at room temperatures. The elastic substrate must have mechanical durability to offer flexibility desired. Now there is developed a method for producing a glass fibre reinforced plastic substrate so that the glass fibres and binding material are arranged to form a layer with a certain content of glass fibres and then the layer is arranged to be pressed to a thickness that is desirable to the substrate sheet.