An electrochemical and X-ray diffraction study has been conducted on the formation of lead dioxide deposits on platinum, from nitric acid solutions, as a function of potential and temperature. It has been shown that these parameters strongly influence the morphology and electrocatalytic activity of the <mml:math display="inline"><mml:msub><mml:mi mathvariant="normal">PbO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>PbO2 films. The electrodeposition process is satisfactorily described by an electrochemical, chemical, electrochemical mechanism: (i) <mml:math display="inline"><mml:msub><mml:mo>H</mml:mo><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>O</mml:mo><mml:mo>→</mml:mo><mml:msub><mml:mo>OH</mml:mo><mml:mrow><mml:mi mathvariant="normal">ads</mml:mi></mml:mrow></mml:msub><mml:mo>+</mml:mo><mml:msup><mml:mo>H</mml:mo><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:mo>+</mml:mo><mml:msup><mml:mi mathvariant="normal">e</mml:mi><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup><mml:mo>;</mml:mo></mml:math>H2O→OHads+H++e−; (ii) <mml:math display="inline"><mml:msup><mml:mi mathvariant="normal">Pb</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:mo>+</mml:mo><mml:msub><mml:mo>OH</mml:mo><mml:mrow><mml:mi mathvariant="normal">ads</mml:mi></mml:mrow></mml:msub><mml:mo>→</mml:mo><mml:mi mathvariant="normal">Pb</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mo>OH</mml:mo><mml:msup><mml:mo stretchy="false">)</mml:mo><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:mo>;</mml:mo></mml:math>Pb2++OHads→Pb(OH)2+; (iii) <mml:math display="inline"><mml:mi mathvariant="normal">Pb</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mo>OH</mml:mo><mml:msup><mml:mo stretchy="false">)</mml:mo><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:mo>+</mml:mo><mml:msub><mml:mo>H</mml:mo><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>O</mml:mo><mml:mo>→</mml:mo><mml:msub><mml:mi mathvariant="normal">PbO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>+</mml:mo><mml:mn>3</mml:mn><mml:msup><mml:mo>H</mml:mo><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:mo>+</mml:mo><mml:msup><mml:mi mathvariant="normal">e</mml:mi><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup><mml:mo>;</mml:mo></mml:math>Pb(OH)2++H2O→PbO2+3H++e−; the second electron transfer stage and <mml:math display="inline"><mml:msup><mml:mi mathvariant="normal">Pb</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:math>Pb2+ diffusion control the dioxide formation in the lower and higher overpotential range, respectively. Temperature and potential (or current) are important parameters in the electrodeposition process. Depending on the potential region, the process can be kinetically or diffusion controlled. In an acid electrolyte, where mainly the <mml:math display="inline"><mml:mi>β</mml:mi><mml:mo>­</mml:mo><mml:msub><mml:mi mathvariant="normal">PbO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>β­PbO2 modification is electrodeposited, the amount of α-phase impurity increases with increasing potential in the kinetically controlled region and decreases in the diffusion controlled domain. In addition, relatively low electrodeposition potentials and high temperatures favor an increase of the crystallite size with preferred crystallographic orientation for both α- and <mml:math display="inline"><mml:mi>β</mml:mi><mml:mo>­</mml:mo><mml:msub><mml:mi mathvariant="normal">PbO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>β­PbO2 modifications. The temperature of the growth solution affects the crystallinity of the resulting oxide deposits and has a marked effect on their performance as anodes in processes at high positive potentials such as ozone generation. © 2002 The Electrochemical Society. All rights reserved.