Anomalous, high-voltage irreversible capacity is observed in electrodeposited and sputtered Sn films when used as working electrodes in electrochemical lithium cells. Sn electrodes can function as expected in Li/Sn cells provided the upper cutoff potential, while removing lithium from the Sn electrode, is kept below about 1.4 V. However, when the upper cutoff potential is increased to about 1.5 V and above, an anomalous irreversible high-voltage plateau in the voltage-capacity curve is often observed during subsequent lithiation. We discuss the relationship between the recharge cutoff voltage and the presence of anomalous high-voltage irreversible capacity. The dependence of the amount of anomalous, high-voltage irreversible capacity vs. discharge rate of the cell is investigated. A model is proposed to explain the anomalous high-voltage irreversible capacity, including strategies to avoid it. One of the strategies is to alloy Sn with Cu. (C) 2003 The Electrochemical Society.