[en] Four calorimetry experiments were performed with palladium cathode electrolysis cells to investigate the possibility of cold fusion heat production based on the reported results of Fleischmann and Pons. Two of the cells contained 6.35-mm-diam x 10-cm-long palladium cathodes in a 0.2-M ⁶LiOD electrolyte; one cell contained a similar cathode in a 0.1-M ⁶LiOD electrolyte solution; and one cell used a cast 1.27-cm-diam x 10-cm-long palladium rod in a 0.2-M electrolyte. All four cells were constructed with platinum wire anodes. One of the cells exhibited an apparent 2--3 W power excess for a period of approximately 300 hours of a total operating time of 1800 hours; each of the remaining cells remained in power balance for the 1800 hour period. 2 refs., 5 figs., 1 tab