We report a new cytoplasmic male sterility (CMS) source in bread wheat (Triticum aestivum L.) designated as msH1. CMS has been identified during the process of obtaining alloplasmic bread wheat in different Hordeum chilense Roem. Schultz. cytoplasms. It was observed that when using the H. chilense H1 accession, the corresponding alloplasmic line was male sterile. This alloplasmic wheat is stable under different environmental conditions and it does not exhibit developmental or floral abnormalities, showing only slightly reduced height and some delay in heading. On examining microsporogenesis in the alloplasmic line, it was found that different stages of meiosis were completed normally, but abnormal development occurred at the uninucleate-pollen stage at the first mitosis, resulting in failure of anther exertion and pollen abortion. Fertility restoration of the CMS phenotype caused by the H. chilense cytoplasm was associated with the addition of chromosome 6H^chS from H. chilense accession H1. Thus, some fertility restoration genes appear to be located in this chromosome arm. Considering the features displayed by the msH1 system, we consider that it has a great potential for the development of viable technology for hybrid wheat production.