A portable powder-liquid high corrosion-resistant reaction cell has been designed to follow in situ reactions by X-ray powder diffraction and X-ray absorption spectroscopy techniques in transmission mode. The cell has been conceived to be mounted on the experimental stations for diffraction and absorption of the Spanish CRG SpLine-BM25 beamline at the ESRF. In the case of the diffraction technique, data can be collected with either a point detector or a two-dimensional CCD detector. Using the 2D-CCD camera, the cell can be used for time-resolved in situ studies of phase transitions and reactions. Powder reactants and/or products are kept at a fixed position in a vertical geometry in the X-ray pathway, which is minimized in order to reduce the X-ray absorption by the reaction bath. Sample is fixed by a porous membrane under forced liquid reflux circulation, assuring total powder-liquid contact, with an accurate temperature control in the range from 20 to 220°C.