Accessibility is often seen to be an important determinant of the location of economic activities. This paper focuses on the specification of accessibility indicators for modelling the location choices of offices, with particular application to the upcoming implementation of a high-speed railway line in the Netherlands. Potential accessibility indicators are formulated, whereby attention is given to the shape of the impedance function and to the role of competitive transport modes in a transport mode's accessibility effect. These indicators are then tested in a discrete choice model on the location of office employment. Finally the accessibility indicators are used to explore the effects of the upcoming domestic high-speed train services in the Netherlands. The analyses show that a Box - Cox impedance function performs best for this application and significantly better than the exponential and power functions. The derived potential accessibility indicators have much explanatory capability for location attractiveness at a regional level, but at an intraregional level connectivity measures become more influential. Finally, it has been found that the accessibility effect of the future high-speed train connection is larger for business travel than for commuting, the value of time of travellers being a dominant factor.