In this paper we consider the problem of robotic search: that is, having a mobile robot find a target object in an unknown environment with obstacles. As a side-effect, the robot explores the environment. Based on previous results, we present a formal description of our problem and an algorithm to solve it. Our work is a derivative of spiral search techniques developed in more abstract contexts. We show that this algorithm has good worst-case performance, in terms of its competitive ratio. We also show experimental data validating the feasibility of our approach and typical results.