... E-mail: chem@surgu.wsnet.ru Received 17th May 1999, Accepted 20th July 1999 Copper(ii) was preconcentrated from aqueous solution on paper filters with chemically attached hexamethylenediamino (HMDA) groups and determined directly on the filters by its catalytic action in the oxidation of hydroquinone with H2O2 in the presence of 2,2A-dipyridyl; the reaction was monitored by measuring the absorbance of wet filters. ... The filter is then dried and the indicator reaction is conducted on the filter. ...