A new method is presented for extracting the intrinsic and extrinsic parameters of electroabsorption modulators (EAMs) from measurements of their electrical to optical and optical to electrical responses over frequency. The method is analytically described and experimentally verified with the use of an electrical vector network analyzer. It is shown that the use of EAMs as both modulators and receivers allows the extraction of the parameters, which govern their intrinsic frequency response while removing the effect of the interconnect/package used and the need for an accurately calibrated optical modulator and receiver pair used to do the measurements. A set of S-parameters accounting for the effect of the interconnect/package is also calculated and used along with the intrinsic parameters to reproduce the measured frequency response of the EAM. Good agreement is obtained between calculated and measured results, thus confirming the validity of the proposed technique.