Abstract: In some critical application areas, it is not allowed to modify the contents of the text, like military, legal and literature fields. Therefore, restoring the original contents of the text becomes a practical and important issue for text watermarking. This study aims to deal with this problem. We firstly present the concept of reversible text watermarking and then bring forth an effective scheme to achieve reversible text watermarking. Based on the synonym substitution method, the proposed algorithm applies an invertible transform to embed watermark, extract watermark and recover the original contents of the text. By using the reversible watermarking scheme, one can not only protect the interests of the author of the text, but also get the original contents of the text, if the receiver has the wish and right to revert the original contents of the text. Moreover, the scheme improves the payload capacity via using high embedding level, compressing the watermark or repeating the algorithm more than one time.