Abstract: In information transmission such as speech information, higher security and confidentiality are especially required. Therefore, data encryption is pre–requisite for secure communication system to protect such information from unauthorized access. In this research, a new speech cryptographic technique based on combination of permutation and substitution of speech samples using chaotic Zaslavsky map is presented. The original speech signal is first, transformed from one dimensional to two dimensional blocks. Then Zaslavsky map is utilized to produce permutation and mask keys to be used in permutation and substitution processes. Third, each block is permuted to shuffle the positions of speech signal samples followed by substitution process to change the values of permuted samples. And finally, encrypted blocks are transformed back into one dimension to produce ciphered speech signal ready for transmission. The results demonstrate that the presented speech cryptosystem provides a high level of security, confidentiality and high intelligibility reconstructed speech signal.