We present medium-resolution ( /A 500) absolute spectrophotometry of 15 bright and cool (N-type) carbon stars. The observations were made with a cooled grating spectrometer within the J ii, K and L' atmospheric windows (1-4.2 ). The observed C stars were AQ Sgr, RT Cap, RV Cyg, RY Dra, S Sct, T Lyr, TX Psc, TW Oph, VAql, V Cyg, VX And, V460 Cyg, Y CVn, Z Psc and WZ Cas. All of them, with the exception of V Cyg, are non-Mira variables and do not show strong infrared excesses, being presumably free of thick circumstellar envelopes. A listing of binned fluxes and the strengths of some molecular features is given, in addition to plots of the flux distributions of the observed stars. For the four stars with measured occultation angular diameters (AQ Sgr, RT Cap, TX Psc and TW Oph), we derive new effective temperatures using our spectrophotometry and the published diameters. Key words: stars: carbon - stars: fundamental parameters - stars: variables: other - infrared: stars.