Since the development of provate property and the rise of the capitalist mode of production, the strangement process has taken on uniquecharacteristics. Specifically in industrial labor, the alienation of workers has reached new dimensions. Human labor became, for the first time in history, a commodity which is exchangeable in the market. The process of labor becoming a commodity was long and complex, and it did not occur without resistance form the workers. This study deals primarily with the historical process of the transformation of labor into a commodity and the implications of this phenomenon to workers´consciounsness. This thesis considers that by examining the ways in wich labor becomes a commodity in an industrial context will help to better understand the characteristics assumed by alienation in subsequent stages of the capitalist mode of productoion where the merchandising of labor has been taken as "natural" or always in existence.