The easy determination of the chemical composition of the plastic components of museum objects has been identified as a critical requirement for the proper preservation and treatment of museum objects with plastic components. To date, chemical identification has been done by wet chemical spot tests applied directly on the object, or by spot tests or instrumental techniques such as IR spectroscopy on samples excised from objects. These methods are not satisfactory. Spot tests are neither comprehensive nor unambiguous, and instrumental techniques are not convenient since the instruments are generally located in analytical laboratories remote from the museum collections. This paper describes the use of a portable FTIR spectrometer with a fiber optic sampling probe to acquire mid-IR reflectance spectra from plastics in museum objects. The technique is non-destructive and is performed on-site at the museum collection. Results will be described with an emphasis on the practicalities of transporting the spectrometer and accessories, and collecting and interpreting spectra.