Spectroscopic studies of the OC:HCCH complex are reported using a continuous supersonic slit jet spectrometer with broadband frequency mode-hop free tunable infrared quantum cascade lasers (QCL), centered at 4.4 and 4.6 mu m. This Letter includes an extended analysis of the nu(3) CO stretching vibration frequency, and investigation of the nu(3) + nu(9) (1) - nu(9) (1) hot band, the nu(3) + nu(9) (1) and nu(3) + nu(8) (1) combination bands for OC-HCCH. The ground state low frequency bend, nu(9) (1), is determined at 20.48361(20) cm (1). The generated rovibrational data is incorporated with previously determined information and used to generate a four-dimensional compound-model morphed potential with radial correction, giving further insight into the molecular dynamics of this complex. (C) 2011 Elsevier B. V. All rights reserved.