We study solutions for a rotating string on S-3 with a background NS-NS B-field and show the existence of spiky string and giant magnon as two limiting solutions. We make a connection to the sine-Gordon model via the Polyakov worldsheet action and study the effect of B-field. In particular, we find the magnon solution can be mapped to the excitation of a spin chain. We conjecture a B-deformed CFT to be the gauge theory dual to this background.
