The aim of this study was the description and assessment of the biochemical and microbiological stability of a semi-fluid spontaneous wheat sourdough, propagated with the same ingredients in two Catalan (Spanish) bakeries over a period of four months. These sourdoughs were initiated two years ago and have been maintained by continuous refreshments with the only difference of blockage temperature and storage time (5 ºC and < 48 h, or 9 ºC and < 24 h). Both sourdoughs have been characterized as sourdoughs with a lactic acid bacteria/yeast ratio of 1.1/1 and with moderate acidity. Between these two sourdoughs significant differences were observed in parameters related with the acidity, the total titratable acidity and the content of lactic and acetic acids. The two sourdoughs studied along these four months were evaluated as stable on time due to the fact that the samples showed low coefficients of variation. Molecular identification of lactic acid bacteria and yeast strains of this suitable consortium in the near future will be further important knowledge for spontaneous wheat sourdoughs.