In this paper we propose and experimentally demonstrate a novel tunable optical dispersion compensator (TODC). Dispersion compensation is achieved by splitting the input signal between two dispersive media, and adding the resulting signals thereafter. Tunable compensation is attained by controlling the power splitting ratio of the input signal between both dispersive media. The frequency response of the TODC is theoretically assessed considering signal addition in the optical and electrical domains. The latter case is enabled by using optical single sideband (OSSB) modulation, which allows preserving the phase information of dispersive media output signals after direct detection. This is the only case experimentally tested, since it avoids stability problems related with coherent addition of optical signals. A TODC with a tuning range of –340 ps/nm to 0 ps/nm was designed and experimentally assessed for a 40 Gb/s non-return-to-zero OSSB signal. The tunable power splitter consisted on an automatic polarization controller and a polarization beam splitter, which offered a tuning time lower than 150 μs. A bit error rate lower than 10–8 was measured on the entire compensation range with a maximum power penalty of 3.3 dB relatively to a SSB signal in back-to-back.