The principal objective of this paper is the study of the arithmetic roundoff error characteristics of several discrete Hartley transform (DHT) algorithms. We first summarize a variety of efficient DHT algorithms including Bracewell\´s original decimation-in-time radix-2 algorithm. Statistical models for fixed- and floating-point arithmetic roundoff errors are then used as the basis for a theoretical study of roundoff noise characteristics of a number of the DHT algorithms. The results of a detailed experimental study of roundoff noise are compared to the theoretical predictions. In fixed-point implementation of the decimation-in-time and frequency radix-2 algorithms, it is found that the noise-to-signal ratio increases approximately 1.1 bits per stage. For the floating-point implementation, the number of bits of rms noise-to-signal ratio for all the algorithms increase as

, so that doubling the number of points produced a mild increase in the output noise.