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We present the results of a search for red QSOs using a selection based onoptical imaging from SDSS and near-infrared imaging from UKIDSS. For a sampleof 58 candidates 46 (79%) are confirmed to be QSOs. The QSOs are predominantlydust-reddened except a handul at redshifts z>3.5. The dust is most likelylocated in the QSO host galaxies. 4 (7%) of the candidates turned out to belate-type stars, and another 4 (7%) are compact galaxies. The remaining 4objects we could not identify. In terms of their optical spectra the QSOs aresimilar to the QSOs selected in the FIRST-2MASS red Quasar survey except theyare on average fainter, more distant and only two are detected in the FIRSTsurvey. We estimate the amount of extinction using the SDSS QSO templatereddened by SMC-like dust. It is possible to get a good match to the observed(restframe ultraviolet) spectra, but for nearly all the reddened QSOs it is notpossible to match the near-IR photometry from UKIDSS. The likely reasons arethat the SDSS QSO template is too red at optical wavelengths due tocontaminating host galaxy light and that the assumed SMC extinction curve istoo shallow. Our survey has demonstrated that selection of QSOs based onnear-IR photometry is an efficent way to select QSOs, including reddened QSOs,with only small contamination from late-type stars and compact galaxies. Thiswill be useful with ongoing and future wide-field near-IR surveys such as theVISTA and EUCLID surveys. [Abridged]

Optical/near-infrared selection of red QSOs: Evidence for steep extinction curves towards galactic centers?