We present an efficient scheme for representing irregular object boundaries which belongs to the grid-based chain coding family. The scheme which is called polycurve codes extends the chain coding family, e.g., chain codes and generalized chain codes, by employing predefined circular-arc segments as boundary approximators in addition to straight-line segments. Each circular-arc segment in polycurve codes is predefined around the associated line segment and labeled as an integer. Polycurve codes enables direct extraction and labeling of high-level line and arc segments from arbitrary boundaries. Once the object boundaries are encoded by poly-curve codes, feature calculation and shape analysis may be done solely based on the look-up table indexed by the integer labels. Experimental results show that polycurve codes improve performance, such as compactness and encoding time, over the existing chain coding family.