Example embodiments disclose methods and apparatuses for encoding and decoding data in a memory system. In an encoding method according to an example embodiment of inventive concepts, a codeword is generated based on a combination of data to be stored and auxiliary data according to stuck cells and an encoding matrix based on information regarding coordinates of the stuck cells and values of the stuck cells. The generated codeword includes data corresponding to the values of the stuck cells at addresses corresponding to the coordinates of the stuck cells. In a decoding method according to an example embodiment of inventive concepts, data may be generated by multiplying an inverse matrix of the encoding matrix used for encoding by the codeword.