Proxy signatures are useful constructions in grid computing, mobile agents and many other emerging applications. In a recent work [Huaxiong Wang and Josef Pieprzyk: Efficient One-Time Proxy Signatures. Proc. ASIACRYPT'03, LNCS 2894, Springer 2003.], Wang and Pieprzyk proposed a one-time signature scheme which allows full delegation to a proxy with an added feature that allows tracing the authorship of the signature in case of a dispute. In this paper we present a simple alternative approach that eliminates public-key cryptography in key generation, offers certainty and simplicity in the dispute resolution and avoids swallow attacks. We also introduce the concept of 1-out-of-n threshold traceable one-time signatures as an efficiency improvement. (C) 2007 Elsevier B.V. All rights reserved.