In this paper, we discuss the properties of making a deterministic algorithm suitable to generate a pseudo random sequence of numbers: high value of Kolmogorov-Sinai entropy, high dimensionality of the parent dynamical system, and very large period of the generated sequence. We propose the chaotic coupled map lattices as a pseudo random number generator. We show what chaotic features of the coupled map lattices are useful for generating pseudo random numbers and investigate numerically which of them survive in the discrete state version of the map. To evaluate the randomness of the bit sequences generated by the RNGs, the NIST suite tests were performed. The proposed RNGs can be used in many applications requiring random bit sequences and also in the design of secure cryptosystems.