Steganography is an important area of research in recent years involving a number of applications. It is the science of embedding information into the cover image viz., text, video, and image (payload) without causing statistically significant modification to the cover image. The modern secure image steganography presents a challenging task of transferring the embedded information to the destination without being detected.In this paper, a DCT based robust methodology has been designed. The cover image is segmented into 8*8 blocks and DCT is applied on the image. The text to be hidden is embedded in the diagonal elements of the blocks by substituting a random variable in place of the bits of the text to be embedded. It is observed that the proposed algorithm is more robust with better CER & Normalized coefficient.