An enormous amount of data needs to be processed in many data mining applications. In addition to algorithmic development, hardware support is imperative to improve the effectiveness and efficiency of these applications. We are investigating various hardware architectural design techniques and methodologies to support data mining at the chip level. In this work, we focus on the design of an FPGA-based processor array for the computation of similarity matrix, a commonly used data structure to represent the similarity among a set of feature vectors, with each matrix element representing the computed similarity measure between two vectors. An algorithm is developed to assign computation efficiently to the array of processing elements. Theoretical performance metrics are derived and compared to the experimental results. Performance gains using the processor array over software implementations are also presented and discussed.